With one connection to a power-hungry or overclocked card your system under heavy load may shut itself down and reboot!
I have to share my case for anyone who is making his build decision or troubleshooting an issue. There are several topics on this forum about it (one pcie cable or two separate, etc.), but they are fairly inconclusive. This one will not fit every instance either, but may save someone his time in a similar situation.
I've got an Aorus Xtreme 2080 Ti from Gigabyte. It's factory-overclocked to 1770Hz boost and has 2x 8-pin pci-e connectors.
Initially I've plugged one 8-pin cable with two connectors between my card and Corsair HX1000i.
But with high graphics preset in Red Dead Redemption 2 I've got instant-reboots of my PC in some cutscenes (including intro) and in the middle of the game. In cutscenes crashes were at the same place everytime: right after when Dutch calls Arthur in the intro or after words "there will be a party!" in another cutscene. Some tweaks in graphic settings helped temporarily (disabling MSAA, lowering shadow quality, changing resolution scale). There were no overheating, as sensors were telling.
After that I tested my system in FurMark. At 720p there were no issues initially. But at 1080p reboot happened again after about five minutes. At another time it was triggered by alt-tabbing out of fullscreen FurMark test. Additionally pressing "reset" button in MSI Afterburner with 720p windowed FurMark in the background would trigger the crash too (consistently), even though I haven't touched any OC controls.
So when I realised the thing about cables and added one, these reboots were gone.
With one cable max power draw from 12V rails of the PSU was about 300 watts (seen in Corsair's Link) when one of the reboots in FurMark happened. After replugging draw was over 360 watts with jumps up to 396. There is a CPU's share in it ofc., HWiNFO tells around (and slightly higher than) 300 for the GPU alone now.
When I was preparing for and building my system, I watched many helpful videos from LTT, JayzTwoCents, Paul's Hardware, Bitwit and others. But that one from Jayz I interpreted wrongly. Since the tests showed real difference (outside of margin of error I think) I should've gone with two cables from the start.
The root cause of reboots themselves may be connected to a PSU playing safe with his over-current protection (and I thank it for that I guess). Or may be it's something else. It would be good to know, but I'm done with hard-rebooting my system. Any insight will be appreciated.
Hope this case will help someone!
