Swapping GPU causing PC to freeze during POST

So I have an older Dell XPS 8940 system that I migrated a 2070 Super into a few years ago and have been using it as my racing sim PC. Just bought a 5070 and a 6pin/8pin adapter and installed the card. I get video, but it causes the system to freeze right when it starts to load windows. I put the 2070 back in and updated to the newest driver with a clean install but Im still having the issue. I thought it might be power but I hooked up my kill-a-volt and measured the 2070 peaking at 213W while booting, put the 5070 back in and it never broke 200. I have a 500w power supply and its the max compatible one Dell makes for this machine but its not coming anywhere close to peak during POST. PC has an 11th gen I7 and DDR4.

Anyone have any tips/suggestions on how to get this working?

I put the 5070 in my main rig and it tested fine so its not the GPU.
Wondering if there is a power delivery issue using the adapter but it looks like the extra pins are just grounds.
I am avoiding doing a clean install because its a pain to setup all the sim software.
There is only a ~25w max wattage difference in the cards, my CPU is only 85w max, 1 NVME and 3 SATA drives (HDD+HDD+ODD), should have plenty of power overhead to spare just to boot.

Can you set the PCI-E gen manually in your BIOS?

Good call

Checked the BIOS settings.
No changes to generation, only able to set resizable BAR and select onboard or discrete graphics.
Current running newest BIOS so nothing I can gain.

gtrguy said:

Can you set the PCI-E gen manually in your BIOS?

Click to expand...

TheGeekFreek said:

Good call

Checked the BIOS settings.
No changes to generation, only able to set resizable BAR and select onboard or discrete graphics.
Current running newest BIOS so nothing I can gain.

Click to expand...

I had the same problem with using a RTX 3070, I had to switch the PCIe lane to GEN3 in order for it to work without randomly crashing all the time.

I'm thinking it's the 500W PSU. If it's happening with both GPU's... it might be going bad.

Transient power demands of 5000 series GPUs are tremendously high compared to earlier gen cards. I recently had to replace an older 1050 watt with a new 1200 watt power supply because it was not responding quickly enough to the transient power demands of my 5090 and was crashing my system(kernel power errors in event viewer). New PSU solved the issue and system runs better than ever. You could try power limiting the 5070 in the Nvidia app to alleviate the issue. System/performance/75%-80% and see if that helps. I did that for a few days and it helped but it still crashed sometimes in MSFS 2020.

Hate Dells stupid proprietary BS.. Bought a 600w PSU that does fit the chassis, but the connectors are slightly different so I cant use it. Thought about getting out ye ol trusty voltmeter and checking the pin-out and rewiring it to match but I dont really have time for that. But my guess is also that its PSU related. Even though the Kill-a-watt isnt showing me that its spiking at all, its really the only thing that makes sense. Have to gut the CPU/RAM/NVME and get a new mobo/psu/case to throw it all in at this point.

That sounds like a what a [H] member would do. Just looked up that dell board and it's a turd. BTW it really requires an oscilloscopes sample rate to catch transients and that's not a standard household piece of equipment for most. Asrock Z590 for $85.00 plus shipping.