hx1200 + 2x 3090 reset

[atao]

Hello,

I've got a system with hx1200 PSU + 2x 3090 + i9 10940.

The system runs fine with certain workloads that appear to smoothly load the GPUs (keep them at high activity) but when i run workloads where the GPU workload is a bit uneven, where the GPU activity is going up and down, the system will power cycle almost immediately.

I've heard that 3090 is particularly challenging due to high transients.

I've tried power-limiting the GPUs and that still eventually power cycles, but just takes longer

Is it possible that I could hook up the PCI 8-pin connectors in a way that's optimal? (i.e. on different rails?)

Thanks,

Andrew

[Corsair Notepad]

The biggest thing would be to make sure you are not utilizing the pigtail connectors on the PCIe power cables in order to connect to and power your GPUs. If you have 3 PCIe power connectors per card you will need to utilize 3 completely separate PCIe power cables from the PSU per card, for a total of 6 PCIe power cables. Using the pigtails connectors will result in the GPUs attempting to overdraw from the single PCIe connector on the PSU resulting in the PSU shutting itself down to prevent damage from occurring to both the PSU and the GPU. 

[atao]

Hi @Corsair Notepad, thank you for the quick response.

I'm not using the pigtails. And each card takes 2 x 8-pin.

I was wondering if i need to keep one GPU on the upper set of PCI PSU outputs and the other GPU on the lower row, if that'd help. Like, separate rails? Or does that not matter?

 

[LeDoyen]

they are all common inside afaik. It's a single 100A rail.

You use the cables that come with the PSU? no extensions?

extensions always cause voltage drop that can cause GPU crashes.

[atao]

I'm using extensions yes. https://www.amazon.com/dp/B08Z5QYMFR?psc=1&ref=ppx_yo2_dt_b_product_details

[LeDoyen]

ah that's FE adapters, not something you cna get rid of quickly..

 

It's worth checking in HWinfo what voltages you get on the PCIE connector of the GPU. It should be as close as possible to 12V.

The cases where you load them steadily and they don't crash, you should see if there's voltage drop. I suspect you may have losses there.

The ATX spec is 11.4V minimum, but you will most likely experience crashes above that.

(i had crashes on a 2080 using extensions, with voltages in the 11,6V range. The 3090 with its transient loads will probably suffer even more from vdrops).

If the voltages are low, you may need to get a couple of these, to cut the losses you have by using an extension adapter :

https://www.corsair.com/us/en/Categories/Products/Accessories-|-Parts/PC-Components/Power-Supplies/12-pin-GPU-Power-Cable/p/CP-8920274

[Corsair Notepad]

16 hours ago, atao said:

I'm using extensions yes. https://www.amazon.com/dp/B08Z5QYMFR?psc=1&ref=ppx_yo2_dt_b_product_details

Try utilizing the FE adapter that comes with your GPUs instead of the 3rd party adapter and see if the issue persists just to make sure its not a quality issue with the adapter. But speaking from personal experience with how much power a single 3090 can use, it is likely that the HX1200 is not able to deal with two of those cards in SLI, as even a single FE card is capable of pulling well more than the 350watt TDP when boosting and under load.