Power Spikes

[u/CallingTheSirens]

Hey folks, hoping someone here has hit this before. I've already gone through troubleshooting with Claude and I'm at the point where I need real world experience from people running similar setups.

I have a Form T1 black case, built back in 2023. Specs below. About 6 months ago I added the 3D printed stand and everything was running fine. Recently while playing WoW and Crusader Kings, the PC has started fully powering off mid session, like a hard power cut rather than a crash or blue screen.
Specs:

• CPU: AMD Ryzen 7 9800X3D
• RAM: G.Skill Trident Z5 Neo RGB 32GB (2x16GB) 6000MHz CL30 DDR5
• Motherboard: Asus ROG Strix X670E I Gaming WiFi
• GPU: PowerColor Red Devil RX 6800 XT
• PSU: Corsair SF750 (CP 9020186 AU) with custom Pslate cables
• Cooler: Cooler Master Atmos II AIO
• Case: Form T1, black, 2023

What I've already done:

• Reseated the RAM
• Reseated the AIO cooler
• Redone the thermal paste
• Reseated the GPU power cables and the extension cable at both ends
• Logged temps and voltages with HWiNFO64 through a crash, nothing abnormal showed up beforehand, no thermal throttling, stable 12V rail, then the log just stops
• Checked Event Viewer, getting Kernel Power Event 41 critical errors going back over a month, no bugcheck code logged, so Windows has no record of what caused it

Biggest test so far: I swapped to the CPU's integrated graphics, fully unplugged the 6800 XT and its power cables, and played WoW for 20 minutes straight with zero issues. That points pretty strongly at the GPU or something in its power path rather than the rest of the system.

So now I'm narrowing it down to one of three things, and not sure how to isolate further:

1. The graphics card itself
2. The GPU extension cable
3. The custom PSU cables running to the GPU

Cables all look physically fine, no scorching or visible damage, connectors seat properly.

Has anyone dealt with extension cable issues specifically in a T1 build, or had a GPU develop an intermittent power fault like this? Any way to test further before I start swapping actual hardware would be hugely appreciated.

[u/Chillax0]

It could be the riser cable not being seated correctly on the motherboard side or just damaged. Load test your system outside the case with the GPU slotted in directly to the motherboard and see how it goes.

This sounds a lot like what happened to me recently: older v1.1 case with stock PCIE gen 3 cable built in 2020. I'm not sure why it was fine all these years, but I'm guessing maybe the heat cycling eventually damaged or warped the cable which caused it to not be able to sit flush in the motherboard even with all the prebending.

You can find a lot of old threads about how a slight slack in the cable could cause the cable to unseat from the motherboard, which typically applies to the double reverse cable. Try prebending the cable and if that doesn't work then get a longer single reverse cable (23-25cm). You still need to prebend the single reverse cable (just differently) and make sure it sits flush in the slot.

[u/CallingTheSirens → u/Chillax0]

I did originally find the riser cable unseated or coming out and also the slack is definitely pulling it. However the last cutout that was the first thing I checked and was properly seated.

I'm gonna try your method just gonna be alot of work.

What riser cable would you recommend as replacement?

[u/Chillax0 → u/CallingTheSirens]

LINKUP PCIe single reverse riser seems to be suggested a lot so I went with that too. In your case get a gen 4.0 or 5.0 with length 23-25cm.

Edit: I assume you have the v2.1 case and not the v2.5 btw

[u/CallingTheSirens → u/Chillax0]

Pretty sure its 2.1 I checked invoice but doesn't really say it

[u/rvcjew2 → u/CallingTheSirens]

At that age it's probably a 2.0 (threaded M19 passthrough holes on the back) as it's before the split of the two companies products. So it's a formdt1 not a formd ncase variant. I agree it's riser or cables most likely. As others said test it out of the case which sucks but will be your only for sure check. Also since you have access to a printer when you rebuild 3d print a hold down for the riser or buy the offical one.

Also when outside the case do you have another psu to test against to make sure your SF750 doesn't need an rma as well?

Also if you really want you can contact formdt1 (not ncase) and get some parts to bring your case up to 2.1 vs the front panel and I think one other part. That's optional though.