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AX1200i PSU Keeps Failing Due to OCP


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I'm currently dealing with a mass failure rate of AX1200i PSUs on my machines. It appears the AX1200i is not ready for any actual heavy use for a 1200W PSU.

Build Specs: (x4 as I have 4 identical machines)
CPU: AMD Threadripper 3970x
MB: Asus Zenith II Extreme Alpha
RAM: 128GB Corsair Dominator 3600
GPU: 2 x nVidia 2080Ti w/ nVLink Bridge (GPU Rendering)
PSU: Corsair AX1200i

Troubleshooting steps taken:
- Removed entire system from case (Rule out possible case shorting issues)
- Removed all but 1 stick RAM

- Reseated CPU (multiple times which is a PITA with the TR design)
- Removed 1 of the GPUs
- Removed all M.2 SSDs / HDDs

After each step, machine will briefly power on, get into Windows, within 5-10 minutes of computer sitting idle, it will simply shut off. At this point, the lights on the MB are still ON, yet fails to turn on with a clicking sound within the PSU.

Remove PSU from case, unplug all cables, use the test button on the back of PSU...first 5 presses results in a click followed by nothing...no light response. After 6 or more clicks of the test button, PSU light will turn Green and the fans spins up and all will be fine. I can press the test button repeatedly after this and all is well. Reinstall PSU and computer will turn on and run between 5 minutes to a few hours before shutting off. Again, machine is typically sitting idle as I don't trust to do anything important on this machine as it's going to shut off at any point.

I currently have 1 sitting in a box next to me to be shipped out for RMA (my 3rd failed AX1200i). I've already RMA'd 2 other units from the other machines...and now my only "new" unit has just failed.

I have the newest "replacement" from one of the other RMA'd units sitting on my desk after only making it 4 days before OCP protection kicks in and essentially makes this PSU a paper weight. I can keep RMA'ing these units, but it's costing me a lot of $$$ by having these machines down and not in production. 3 of the 4 machines are all down with dead AX1200i PSUs. I'm obviously beyond my refund period, as it's at least a two month process to get a recertified unit from Corsair...even then, the likelihood of this PSU making it another week before it's dead leaves much to be desired.

Is this a design flaw with this power supply and modern HEDT builds?

I have an older AX1200 (non i version) sitting in an older dual Xeon workstation and I installed it on my open bench TR machine and it's been working fine without issue, for almost a week now. (It's a record! 😄 ) So I know my hardware is just fine, but this AX1200i just seems to be garbage! I love Corsair PSUs and they've done me solid for 10+ years...but man...I'm not sure what to do at this point.

Anything I'm missing from a setup point that I could try and change before it shuts itself off? I've already tried switching to Single Rail from Multi-Rail OCP, but that didn't seem to make any difference...as the machine shut off minutes later.

I really don't feel like spending $2k on new PSUs when I already have 4 that should just work...or am I just SOL?

Any insight would be greatly appreciated!! Thanks all!

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  • Corsair Employees


How do you have the PCIe cables going from the PSU to the 2x 2080 Ti's?  You should have four separate cables, each with two connectors on them.  If you were to use only one connector from each cable, rather than two, does the problem change?



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17 hours ago, Corsair Elito said:


Can you send me your previous RMA numbers, we would like to look into this issue for your further, Thank you.


Let me look back into my records and see if I can pull those numbers up for you. I just have the RMA # handy for the one sitting on my desk to be shipped in for repair. Current RMA#: 2004616696
Late 2020 RMA#: 2001391804

That was the only past RMA number I could find, looks like I may have used my work e-mail for a few of those and just recently switched jobs.

I'm also willing to do some testing on my side should you have any thoughts or questions on the setup. I could fully document everything with pictures to try and help figure out this problem...as it appears only on my AMD TR systems with 4 different MBs. I'm willing to help continue troubleshooting to get to the source of this strange issue.

@JohnyGuru: I'm currently running 4 individual 8-pin connectors, 2 to each GPU. I've read this could have been an issue and so this is what I've done. I also have 2 PCIe 8 Pin cables going to my MB as it also needs a little extra power beyond the typical 4+4 CPU cable.

Here's the crazy part about all of this...as long as my computer is running FLAT OUT with 100% CPU and/or GPU usage...there are ZERO problems. All my problems are when the machine is sitting idle...this is when it will shut off and then I can't turn it back on without the process of pulling the PSU, hitting the test button until it consistently tests green.

The other suggestion I got was to go into iCue and adjust the PSU back to Multi-Rail OCP, then setting all of the various settings to full 40A. Then I set the fan to a fixed speed of 65% just to make sure it's not cooking itself...but temps have been reasonable 35C almost all the time even when under full load from the system.

Lastly, I also changed where the PCIe connectors were plugged into the PSU. Originally I was using spots 1-6. Now I'm using plugs 1, 2, 4, 5, 7, 8. I'm skipping 3 and 6 in the hopes I can better spread out the power draw demand on the PSU. Additionally, I added 2 more SATA power cables to split the number of fans / AIO power. 2 cables are being used for fans / AIO, then a dedicated cable for the single 12TB HDD used for backup and general storage.

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Just an update on this situation.

I just put in one of the new refurbished units sent, and it exhibits the same problem within the first 45 minutes of use. PSU powers off, and refuses to turn back on, yet all of the LEDs and LCD screen on the MB are still lit up and active as though I simply pressed the power button. So weird!

For the time being, I've swapped out the AX1200i for another brand 1200W PSU and it's been working great for almost 1 full day...so hopefully this will give me more data points in solving this problem. Thank goodness the case I'm using has a good layout making swapping a PSU not too painful.

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I have a few moments to fully test out the PSU tonight and here are some results of my tests.

PSU PCIe / GPU plugs 1-8:

  1. MB CPU 4+4 Bottom
  2. MB CPU 4+4 Top
  3. MB 6-pin Aux
  4. Empty
  5. 2080ti GPU1 Inside
  6. 2080ti GPU1 Outside
  7. 2080ti GPU2 Inside
  8. 2080ti GPU2 Outside

At idle, monitoring the Amp draw from within iCue software AX1200i device settings, everything looks pretty normal. 5-8 are sitting at 6-7A on each plug and don't really deviate too much with normal computer use.

When GPU rendering, this is another story. I will see a little fluctuation on plugs 1-3 anywhere from 0-9A draw and it kind of bounces around. Spikes will jump up and then drop almost immediately. Plugs 5-8 will jump up a little bit and hover around 8-9A on each plug...but there are times where these cables will spike upwards of 21-22A and then drop immediately down to the 11A or so.

I don't know how accurate those measurements are within the iCue software, but that's what I'm seeing. I can get about 20 minutes of GPU rendering before the machine will power itself down and the PSU will no longer power the machine back on. All my temps are good too. PSU temps range from 30C-33C and I have the fan set to 80% fixed speed. CPU is hovering in the 50C range which is pretty good for a 3970X. GPU temps are between 70C-75C when flat out rendering at 100% usage on both GPUs. (2 x 2080Ti). RAM temps are in the low 40C range...never higher than 42C on any of the 8 sticks (128GB total).

I ended up putting back in the other brand 1200W PSU and it's been rendering for about 3 hours straight with no issues...it will be rendering for the next few days, as I have a few large jobs to get out and can't be messing with the PSU and constantly worrying when the machine is going to shut off.

I hope this helps anyone else who may be struggling with this issue.

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