[SOLVED] PSU shutting off PC when gaming

[NortheastYeti]

First time building a PC from scratch, and first time posting here. After completing my build, the PC was running really well when handling non-gaming activities, but now it seems that any time I throw a demanding title at it (ex. Cyberpunk), power will eventually cut out entirely. Sometimes this takes 5 mins, sometimes it takes 30.

Specs:
CPU: Ryzen 9 5900x
Cooler: Corsair H150i Elite Capellix (360mm AIO)
Motherboard: ASUS ROG Crosshair VIII Hero (WI-FI)
RAM: T-Force Xtreem ARGB DDR4 3600MHz CL14 32GB (2x16GB)
SSD/HDD: WD_BLACK SN850 NVMe 500GB, WD_BLACK SN850 NVMe 1TB
GPU: ROG Strix RTX 3080-O10G
PSU: Corsair RM850i - 80 PLUS Gold
Chassis: Corsair 5000x
OS: Windows 10 (Version 10.0.19043 Build 19043)
Other: Lian Li Strimer Plus 24pin ATX extension, Lian Li Strimer Plus Triple 8pin PCIe extension

Some additional information:

• CPU, GPU, and motherboard temps are typically all under 70c when it fails
• Not overclocked other than enabling DOCP, in order to achieve 36000MHz RAM speeds @ 1.45v
• Both the motherboard and GPU have added Lian Li Strimer Plus RGB cable extensions, using 3 separate sleeved PCIe cables between the power supply and the RGB extension for my 3080

I am currently trying to test a number of different points of failure, but haven't discovered the fix yet. I would also be willing to undervolt my GPU, but even so, would like to determine if I have a specific problem before looking for a workaround.

• I have gone from 8pin CPU power to the optional 8+4 configuration
• I have tried different outlets in different rooms
• I have yet to try to remove the RGB cable extensions from the system
• I have yet to try another PSU, as I don't have another around with a high enough wattage
• I have yet to replace the thermal paste, but the temp readings made me feel like this was the last thing I needed to try

I've seen similar posts to this one, but I don't necessarily see consistent resolutions. Any advice would be appreciated.

 

[JohnBonhamsGhost]

be sure you are using separate PCIe cables for GPU power and not a single cable with daisy-chained connectors.
if so, next troubleshoot should be trying it without the extension cables.