Reviewer: OklahomaWolf
Product: Corsair AX1200 1200W
Product Link: http://www.corsair.com/products/AX1200/
Supplied By: Corsair
Price: $329 MSRP
Introduction
Once in a while, something really cool comes into the lab here for me to look at. Today is one of those days. Corsair just dropped their latest and greatest into my hands, a 1200 watt model that just so happens to be rated at 80 Plus Gold, and I'm going to see just what it can do. Come on in - this should be fun.
Page 1 -
Good day to you, my good readers. As you can see by the picture above, I'm reviewing a house today. It's a rather nice house from outward appearances, adding up to 1200 square feet on each of its two main levels, and comes with three bedrooms and two and a half baths. It's located in a wonderful neighborhood, close to schools and shopp... wait... that's not a house, is it? Glasses... glasses... where are... ah, here we go.
Well, would you look at that. That's definitely not a house. It's just a power supply box the size of one. Corsair's sent me their latest and by far their greatest today in the 80 Plus Gold rated AX1200.
First things first. Let's examine the back of the box where all the marketing goodness is. Since this box is approximately the size of the John Hancock building in Chicago, there's no chance any of you will be able to make out that printing. So, I'll type it all out for you:
- Unprecedented Power Protection.
The AX1200 pushes the state of the art for reliable delivery of clean power under imperfect conditions. If you require mission-critical stability or you simply want one of the best power supplies available, the AX1200 is for you. - A True Modular Cabling System.
With the AX1200, all cables detach from the power supply. During installation, this gives you the flexibility of using only the cables you need for a clean system build with optimal airflow. And, when it's time to replace or upgrade your power supply, it can be removed from your system without interfering with your cabling - the cables stay in place and connect to your new fully-modular Corsair power supply. - Incredible Efficiency.
With 90% efficiency at 50% load, the AX1200 runs quieter, generates minimal excess heat, and saves you money every month. It's earned the 80 Plus Gold seal of approval, your guarantee that you're making the right choice for smart, efficient power delivery. - The Corsair Advantage
With more than 15 years of building enthusiast-grade memory and components, we've earned a reputation for quality, compatibility, and performance. Need help? We're available by phone call, email, or web forum. - Learn more about the pioneering technology that goes into the Professional Series Gold AX1200 by reading our white paper at: corsair.com/products/AX1200
Oh, goody! A white paper! For electronics nuts like me, white papers are cool. Let me just go over to the link and see... huh. No white paper. Maybe they're still getting it ready. This is a brand new product, after all. Let me check my reviewer's guide and see if there are any clues in there. Interesting... the reviewer's guide says that this unit utilizes synchronous rectification on the outputs and ZVS/ZCS (zero voltage/zero current switching) on the primary side to help it attain its remarkable efficiency. Often, the letters ZVS and ZCS go together with LLC resonant topology, like we saw in the Seasonic X650 way back when. As you will recall, that unit was among the very first 80 Plus Gold units to market. It will be interesting to get this puppy apart to see how it's made.
Meantime, let's take another look at the above picture. There are pictures of the connectors along with a count of how many come with the unit, a simple load table, and a couple of graphs representing noise and efficiency. In the event you don't speak english, the marketing points I reprinted up there are also present in French, German, Spanish, and Italian.
What you're seeing right now is one of the two sides of the box. The opposing side looks exactly the same.
This side of the box right here has a few more marketing points, as well as a few fancy logos. One of these indicates that in buying this unit, you're getting a seven year warranty. Nice. Here are the extra marketing points:
- Mission-Critical Stability
Leading-edge technology ensures performance under adverse conditions. - Unprecedented Flexibility
The 100% modular cabling system makes installation, customization and replacement easier than ever. - Industry-Leading Protection
Backed by a seven year warranty and legendary Corsair support.
I hate to tell you this, Corsair, but that unprecedented flexibility? It's... uh... precedented. See here and here and here. In fact, it's so precedented that Ultra Products has the patent on the modular cabling. And maybe it's just me, but I was somewhat expecting a little blurb about the protection circuitry present inside the unit, rather than a comment about the warranty. At this power level, I like protection circuitry. That warranty is pretty cool though, one must admit.
Another side of the box, and some more marketing. Here you go:
- Auto-switching circuitry provides universal AC input from 90V-264V
- Supports ATX12V 2.3 and EPS12V 2.91 standards. Backwards compatible with ATX12V 2.2/2.01
- Dimensions: 150mm x 86mm x 200mm
Time to open the box. Hooray! Ah, look... there's a phone book in there.
Interesting - this phone book appears to have instructions, tables, and a big list of - sigh - more marketing points. Oh, very well - I'll reprint them too.
- It supports the latest ATX12V v2.31 and EPS 2.92 standards and is backward compatible with ATX12V 2.2 and ATX12V 2.01 systems.
-Nothing new here - we already saw this on the side of the box. Next. - An ultra-quiet 140mm double ball-bearing fan delivers excellent airflow at an exceptionally low noise level by varying fan speed in response to temperature.
-I hear some of you asking whether or not I plan to verify this claim. Well, not really. You see, when you load test something in my lab, you almost need hearing protection already from the other bajillion fans running at the same time. You could fire up a jet engine in there and I wouldn't hear it, let alone an "ultra-quiet" 140mm fan. - Up to 90% energy efficiency at real world load conditions means less heat generation and lower energy bills.
-We'll see how accurate this claim is during the load testing, as usual. - 0.99 Active Power Factor Correction provides clean and reliable power.
-Actually, it does more for the AC utility than it does for the output of a power supply. This is also the circuit responsible for that universal AC input the box spoke about. - Universal AC input from 90-264V. No more hassle of flipping that tiny red switch to select the voltage input!
-See my comment above. - A dedicated single +12V rail offers maximum compatibility with the latest components.
-It can, I will agree. However, I know of no units in this power range that hinder compatibility based on the number of 12V rails. A few early units did it wrong, but engineers quickly learned to do it right. I'll get more into this later. - Over-voltage and over-power protection, under-voltage protection, and short circuit protection provide maximum safety to your critical system components.
-Ah, there's that blurb about protection circuitry I was looking for. No overtemp protection or overcurrent protection, it would seem. - High-quality Japanese capacitors provide maximum safety to your critical system components.
- The completely modular cable system allows you to use only the cables you need. Power supply upgrade and replacement is easy, as the cables only need to be disconnected at the power supply.
-I have to admit, I do like a completely modular unit. They're easier to take apart on page four of each review. And Corsair does make valid points here, as long as the cabling on this unit remains compatible with future units. - Low-profile, flat cable design reduces air friction and helps maximize airflow through your computer's chassis.
-Corsair's approach here is reminiscent of Ultra's "FlexForce," where the modular cables are done up in black ribbon cable. Some people like this approach, others don't - mostly because you can't tell which wires are which. I happen to like the idea. - A Seven year warranty and lifetime access to Corsair's legendary technical support and customer service.
As you can see here, the box came packed with a power supply in its own velvet PSU cozy, a 14 gauge power cord, a bag of modular cables, the New York City yellow pag... er... manual, some zip ties, and a case badge.
Here's the power supply itself, done up in that matte black color I like so much.
Another angle. You can see the big round metallic sticker on the back that proclaims that the unit does make use of Ultra's patented modular cabling system.
The exhaust grille is nice and unrestricted with a nice solid feeling power switch next to the AC receptacle. No wimpy little toggle switch for this bad boy.
The label, done up in black, white, and gold looks rather tasteful to me.
Here's the fan for you. This unit is so big, it makes a 140mm wind machine look small, doesn't it?
Here's the label, and the load table printed on it. As you can see, there are some odd numbers there. This is not, in fact, a 1200W unit - it's a 1204.8W unit. Huh? Why the odd number, Corsair? The unit can't do another 0.2 watts or something? Ah well - I'll test it according to these numbers and see what happens.
I wanted to take a moment to comment on that single massive 100.4A 12V rail. I've been seeing a backlash against multiple 12V designs, and I feel some comment from me is timely; though I've written about this before. As of right now, this is the largest single 12V design I've tested, with the Silverstone Zeus ZM1200M coming in a close second and Ultra's X4 1200W unit coming in third. I have mixed feelings about this. One one hand, I know why the single 12V rail is there and how it came to be in the marketplace. But on the other hand, it makes me a mite nervous. 100.4A is an awful lot of current. You can melt the insulation on some seriously thick gauge wires with that, never mind the 18-16 gauge wires most power supplies this size use to connect to your computer parts. Direct short circuits shouldn't be too much a problem, but what if something doesn't fail in a direct short? What if something partially fails, starts drawing massive 12V current through three or four small wires, and yet doesn't overdraw that 100.4A rail? There is a risk factor here when you start getting 12V rails this huge, people, whether you're talking about a Corsair, Ultra, PC Power and Cooling, or any other company's single 12V design. It's still a reasonably minor risk on a well built unit like this, but a risk is present nonetheless. My rambling point is this - multiple 12V rails aren't the devil, folks, especially on units that can pull more power out of the wall than your toaster.
I rather prefer the way Silverstone did it on the 1200 watt Zeus, with a switch you could use to implement multiple 12V rail overcurrent protection as desired. Personally, I would make use of such a switch for anything that's really "mission critical," like a server stuck in the back of a closet somewhere that has to run unattended for years. Memory tells me that Silverstone shipped those units with them set to single 12V, for the enthusiasts who like the idea of a single 12V rail this size. If I were working for Corsair, I would consider adding just such a feature to future units of this size. We'll have to find out on page four whether or not this kind of thing could be implemented easily on this particular unit.
Oops... looks like when I had my glasses off I picked up my "old codger" hat by mistake instead of my "harmless eccentric" hat. That explains the itching and the desire to go yell at people to get off my lawn. If y'all would like to buy a single 12V @ 100.4A power supply, don't let me stop you.
| Corsair AX1200 | +3.3V | +5V | +12V | -12V | +5VSB |
| 30A | 30A | 100.4A | 0.8A | 3.5A | |
| Max Power | 180W | 1204.8W | 9.6 | 17.5W | |
| 1204.8W | |||||
Here are the modular cables for you. Not all of them are done in flat black ribbon cabling - some are done in sleeved ribbon cabling.
Use approved AX1200 cables only. We'll have to take care in the future when it comes to Corsair's marketing of the full modularity... this seems to tell us that compatibility will be limited.
| Type of connector: | Corsair AX1200 |
| ATX connector (600mm) | 20+4 pin |
| 4+4 pin EPS12V/ATX12V connector (610mm) | 2 |
| 6+2 pin PCIe (610mm) | 6 |
| SATA (440mm+90mm+90mm+90mm) | 12 |
| SATA (400mm+90mm) | 4 |
| 5.25" Drive (460mm+110mm+110mm+110mm) | 12 |
| 5.25" - 3.5" Drive Adapter (100mm) | 2 |
| Unit Dimensions(L x W x H) | |
| 200mm x 150mm x 86mm | |
Once again, Corsair had decided to do away with those tiresome hardwired 3.5" drive connectors on this unit, instead throwing in a couple of adapters. This is something I would like to see more of from Corsair's competition.
Page 2 -
Let's get started on the load testing phase of the review, shall we? As always, a SunMoon SM-268 will be doing the major load testing for this experiment. Since this is a very large capacity power supply, the SunMoon has brought along three of its friends - a trio of auxiliary 12V load banks. Together, they are able to load up to and over 130A of 12V capacity. They will be joined by some other goodies, namely a Brand 4-1850 power meter, a multimeter, a dual probe thermometer, and a USB Instruments Stingray DS1M12 oscilloscope.
Now, most of you reading these words have already become familiar with my testing methodology. To be honest, I'm going to push the lazy button this time and not get into the whole deal on this review. I'm anxious to see how this unit will perform, and so are you. That being said, I...
"Hey!"
Huh? Who said that?
"Down here!"
Oh... it's my Stingray oscilloscope. What do you need, Stingray? I'm in the middle of a review here.
"Just what is that thing doing here? Don't pretend you don't know what that is. That's a Tektronix TDS-2012B. You... you're replacing me, aren't you? Don't shake your head at me, admit it! After all the power supplies I tested for you, you're just going to dump me for the latest model, aren't you?"
Heh... d... don't be silly. I'm not replacing you. That's, uh, a replica. Yeah, that's it.
"Replica, my left BNC. You're replacing me and you won't admit it."
Look, can't we just get through this review? I promise I'll talk to you later.
"Okay. Fine. But you have some serious explaining to do. Buddy of mine? He's an old CRT model and probably weighs more than you do. You mess with me, you're messing with him."
Folks, let's get the load testing started so I can think of a lie, fast.
"I heard that!"
Uh... I... just said, I'm thinkin' some pie is best. Whew... that was close.
| Results from Corsair AX1200 COLD load tests | ||||||
| Test # | +3.3V | +5V | +12V | DC Watts/ AC Watts | Eff. | Intake/ Exhaust |
| Simulated system load tests | ||||||
| Test 1 | 2A | 2A | 18A | 238W/ 269W | 88.5% | 22°C/ 22°C |
| 3.35V | 5.02V | 12.03V | ||||
| Test 2 | 4A | 4A | 36A | 473W/ 525W | 90.1% | 23°C/ 24°C |
| 3.33V | 5.01V | 12.01V | ||||
| Test 3 | 6A | 6A | 55A | 722W/ 784W | 92.1% | 23°C/ 25°C |
| 3.32V | 4.99V | 11.99V | ||||
| Test 4 | 8A | 8A | 74A | 967W/ 1059W | 91.3% | 24°C/ 27°C |
| 3.30V | 4.97V | 11.97V | ||||
| Test 5 | 10A | 10A | 91.8A | 1199W/ 1338W | 89.6% | 24°C/ 28°C |
| 3.28V | 4.95V | 11.95V | ||||
| Test CL1 | 20A | 20A | 6A | 242W/ 294W | 82.3% | 24°C/ 26°C |
| 3.27V | 4.96V | 12.03V | ||||
| Test CL2 | 0A | 0A | 100.4A | 1201W/ 1304W | 92.1% | 24°C/ 28°C |
| 3.33V | 5.00V | 11.96V | ||||
Good golly! Look at that efficiency! Awesome! Folks, I have a confession to make. Yonder Diablotek from a few weeks back up and toasted my Brand 4-1850 meter, and it took me a couple weeks after this here review went up to notice it was reading ever so slightly off during this review. So, I've gone back and plugged in the numbers from the Kill-A-Watt instead, which as it turns out was not damaged with the Brand. Even so, we still get 92.1% efficiency on this unit there in test three, a number I like very much.
And take a look at the voltage readings. I've seen stability like this before, folks, but seldom on a unit this size. The 12V rail, which sees nearly a 74A difference between tests one and five, is still managing to get away with 1% or better voltage regulation. That's quite an accomplishment for any unit. The 3.3V and 5V rails have slipped outside of 1% regulation, but haven't gone too far.
Sorry I haven't got too many other comments right now... it's taking some time to get over those efficiency numbers. Wow. Friends, it used to be when I saw numbers like this, I would start cracking open the SunMoon looking for failed MOSFETs, for that used to be the only way to explain these numbers. Well, neither the SunMoon nor the auxiliary loaders can be blamed this time - I verified the working order of everything in the lab before I started this review. Nope, you're just going to have to blame this one on some very capable engineers, because this thing really is this efficient.
| Results from Corsair AX1200 low load test | |||||||
| Load Level | +3.3V | +5V | +12V | 5VSB | -12V | DC Watts/ AC Watts | Eff. |
| 10.1% | 1A | 1A | 9A | 0.5A | 0.2A | 122W/ 145W | 84.1% |
| 3.36V | 5.03V | 12.03V | 5.08V | -12.11V | |||
Moving on to the low load test, we get another very nice but not altogether surprising efficiency number. This is not Gold performance here. Why is this nice? Well, it's still just about at Silver. Why is that nice? Consider this - the nature of the SMPS is to be less efficient the lower the load. Units that are optimized to pass at a certain 80 Plus certification level are always less efficient down here around the 10% mark. This is because 80 Plus doesn't get into gear until they set their lowest load to 20%. On units this size, that means they don't start testing until the unit is loaded to 240 watts. As this is well above what most computers draw at idle, I started doing this test to give you a better idea what you can expect from it at idle.
And from this unit, you can still expect well over 80% efficiency here. Very, very nice.
| Overshoot Transient Testing - Corsair AX1200 | |||||||
| VSB On | VSB to Full, 12V | Off to Full, 12V | |||||
 |  |  | |||||
You will recall that from these three tests, we want to see turn on spikes that go no further than 10% over mean value, or 5.5V when it comes to that first shot of the 5VSB rail. But the good news is, the spike doesn't come anywhere close. There is a spike, but it's really more of a blip. The 5VSB rail blips just a fraction of a hair over the 5V mark, holds at the 5V mark for a second, and then gently settles down for the long haul at just under that mark. That's pretty good, considering the unit is fully loaded for these tests with a 5VSB load of 3.5A.
Over in the two 12V shots, where the most action is, there's no spike at all. The unit rises gently and gracefully from nothing to its final 12V operating value. This is most excellent performance indeed.
Page 3 -
And now for the real fun stuff - the hot testing. You may remember that my hot box is a modded ATX case with ductwork running to the SM-268's exhaust fan. This allows the box to heat up according to how much loading the SunMoon is doing. Since a lot of this unit's capacity is being offloaded to the auxiliary load banks, the ambient temperature in the box will be somewhat lower than usual. So, I'll leave the exhaust fan on and turn off the intake fan. That should do the trick.
| Results from Corsair AX1200 HOT load tests | ||||||
| Test # | +3.3V | +5V | +12V | DC Watts/ AC Watts | Eff. | Intake/ Exhaust |
| Simulated system load tests | ||||||
| Test 1 | 2A | 2A | 18A | 238W/ 269W | 88.5% | 27°C/ 27°C |
| 3.35V | 5.02V | 12.02V | ||||
| Test 2 | 4A | 4A | 36A | 473W/ 528W | 89.6% | 34°C/ 36°C |
| 3.33V | 5.00V | 12.00V | ||||
| Test 3 | 6A | 6A | 55A | 721W/ 788W | 91.5% | 38°C/ 42°C |
| 3.32V | 4.98V | 11.98V | ||||
| Test 4 | 8A | 8A | 74A | 966W/ 1063W | 90.9% | 41°C/ 48°C |
| 3.30V | 4.97V | 11.96V | ||||
| Test 5 | 10A | 10A | 91.8A | 1198W/ 1346W | 89.0% | 44°C/ 53°C |
| 3.28V | 4.94V | 11.94V | ||||
| Test CL1 | 20A | 20A | 6A | 241W/ 295W | 81.6% | 32°C/ 36°C |
| 3.27V | 4.94V | 12.02V | ||||
| Test CL2 | 0A | 0A | 100.4A | 1200W/ 1323W | 90.7% | 40°C/ 48°C |
| 3.33V | 4.99V | 11.95V | ||||
Ok, I'm just going to take off my "harmless eccentric" hat and put on my "whoopin' and hollerin'" hat now. Be right back.
I'm back. Guys, the whoopin' and hollerin' is a lot more fun when you don't have a seven foot six inch ceiling height to deal with. My head's going to be hurting for a while. But certainly, it won't be from these numbers we're seeing. This is one big bad unit, that's for certain. Not even the hot box could get it to go below Gold efficiency in the progressive tests, and even in the 12V crossload test, where I had only the 12V rail loaded to full power, the unit is still pushing 91%. I have a feeling it's going to be a while before I see anything best these numbers.
And the voltage readings - what more can I say? Stable as the day is long. 12V rail is still pulling down 1% stability, while the other two are still just outside that mark. Awesome, awesome, awesome. Let's look at the scope shots provided by our most excellent Stingray to see how much more awesomer this unit can get.
| Oscilloscope Measurements - Corsair AX1200 | |||
| Test # | +3.3V | +5V | +12V |
| Test 1 |  |  |  |
| Test 2 |  |  |  |
| Test 3 |  |  |  |
| Test 4 |  |  |  |
| Test 5 |  |  |  |
| Test CL1 |  |  |  |
| Test CL2 |  |  |  |
The AX1200 can get this much more awesomer. How does 29mV of ripple at full power sound to you? Sound good? Well, what you're actually seeing is the worst of it. Most of the time, at test five, this unit sat there at 20mV or less on all rails and stuck its tongue out at me. But, at regular intervals, the ripple would jump to the readings you see above. The 5V and 3.3V rails did the same thing. This is not a problem though... we're talking less than 15mV of swing on a unit already so far in spec it's crazy. This is likely a side effect of the switching topology used. We'll get a little more into that on the next page, after we finish looking at these ripple shots.
"I'll ripple you."
Sigh... Stingray, I said I'd talk to you later.
"I'll ripple my USB cable right upside your head, how'd ya like that?"
Guys, I think the Stingray's a little angry right now. We'd best let him cool off. Let's take this over to my workshop now, shall we? What? Oh... it's that room over there on the left cleverly disguised as my bedroom. Mind the collection of dust bunnies on the floor - those take a while to get just right.
Page 4 -
Yate Loon is our fan of the moment.
Well, now - that's certainly a different looking unit, isn't it? You say you don't recognize the layout as either Seasonic or CWT, like the rest of Corsair's units? That could be due to the fact that Corsair went to a new OEM on this one, Flextronics. And I'm just going to 'fess up right now - I am not desoldering all that stuff in there. Much of the electronics should be identifiable using clever camera angles and a lot of hard squinting.
This unit comes with a line filtered AC receptacle, the way many high grade server units do. These incorporate many of the parts found in the usual AC transient filter into one little box along with the receptacle itself.
The soldering on this unit is very high quality, among the best I've seen.
This is the PWM controller for the unit, or so it would appear. It is a 3843B current mode controller.
Here's the modular connector panel. Some seriously large metal pieces are employed as conductors to help move the voltages to the pins that need them.
Behind the modular connector panel, we see the Rubycon electrolytic capacitors used to filter the 12V output. What you can't see in this picture are several large shunt resistors near those big 10 gauge wires, which are usually used to provide multirail overcurrent protection. So, it's looking to me so far like this unit does have the ability to add that switch I was talking about on page one.
This unit uses the VRM approach for all three main rails. This is the back of the 3.3V VRM. A 1587A controller, two K0391's and two K0394's handle this VRM. The 5V VRM has a similar silicon compliment.
That PCB right in the middle of the picture handles the protection duties, and then some. A Weltrend WT7527S handles the overvoltage and undervoltage protection on the unit. It also has overcurrent protection capabilities for up to two 12V rails.
Two of these were also found on this same PCB. I couldn't find a datasheet for them. Two HC74AG chips were found on the backside of the PCB.
Primary side switchers are these here 6R125P's. There are four of them. I could not identify the PFC components - desoldering the transistors would have killed the unit due to SMD components that were entirely too close for comfort. It's too nice a day to go around killing units this awesome on purpose.
This is the front of the 3.3V VRM.
What you're looking at here is the backside of the 5VSB board. Fan control is also located here.
Out front, there are some transient filtering components. Two coils, a MOV, four Y capacitors, and two X's.
Last but not least, we have the double VRM for the 12V rail. A 2812 controller can be found on each side, along with what appears to be four (total of eight) Infineon BSC019N04NS power transistors.
Page 5 -
Performance (40% of the final score) - oh, this one's easy. 10.
Functionality (20% of the final score) - Corsair was thinking of pretty much everything when they drew up this unit. It's fully modular, has that nice flat black cabling to help with cluttered cases, and has enough peripheral connectors to satisfy almost everyone. Going to have to do 9.5 here, because I'd like to encourage the addition of a multirail OCP enable switch on units this size.
Value (30% of the final score) - Corsair expects these to hit the streets for around the $300 mark, with the MSRP being $329. Over at Newegg, this would make the unit a fair bit cheaper than the reigning king of the hill in the Silverstone ST1500 and competing a little bit on the high side with the other 1200W+ units being sold there. But, one must also remember that this is currently the only Gold rated 1200W unit being released right now. That makes this unit a very good value indeed. 9.5.
Aesthetics (10% of the final score) - no complaints here. I like the way it looks a whole lot. 10.
| Performance | 10 |
| Functionality | 9.5 |
| Value | 9.5 |
| Aesthetics | 10 |
Total Score | 9.8 |
Summary
There is a whole lot to like about the new Corsair AX1200, and very little indeed to hate. Lots of power, lots of connectors, and all of those connectors come off if you want them to. And we can't forget about the efficiency, which just about outclasses everything else I've ever tested. Do you need any other reason to buy one? Let's face it - Corsair's new baby is made of awesome sauce, and I know you all want a taste. Stop reading my review and buy one, already!
The Good:
- among the highest efficiency I've tested to date
- extremely low ripple
- lots of connectors
- fully modular
- very stable
The Bad:
- somehow, they're going to have to top this one... eventually
The Mediocre:
- single 12V rails are nice... to a point. I think we're getting real close to reaching that point.
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