Question PC Powers Off Frequently?

[Timmah200]

Hello everyone! I'm new to the forums. Before we get to the issue, here's a very bare-bones summary of my build:

ASUS ROG Strix X-570E
AMD Ryzen 3950x, not over-clocked.
64GB RAM (2x32GB Sticks)
Nvidia RTX 3090
LG 27GN950-B 27-inch 4k Monitor with 1ms Response, 144Hz refresh, Nano IPS, G-Sync
Phanteks 1000w Gold-Rated PSU
Windows 10 Home

So, my custom build PC powers off frequently and reboots itself. I know it's not overheating (using MSI Afterburner to monitor). This is probably my 7th or 8th build in the past 15 years, so I have experience. I've had this build about 18 months or so, maybe a bit longer? Here's the weird details, though:

1. It only reboots itself right after I turn it on...it'll power down and reboot 2-4 times in a row all by itself.
2. It'll reboot itself after waking up from sleep, again, 2-4 times in a row.
3. When it reboots, it's not the "Windows is rebooting" cycle or an automatic update, it's almost as if it's losing power, like there's a short. I checked for shorts with a volt meter...nothing.
4. RARELY, I'll get the "recovery mode" blue screen, asking me if I want to go into safe mode because my machine wasn't shut down properly. I just boot normally with no issues.
5. Whenever I am actively using software, be it a graphically intensive game, word processor, browsing the internet, etc., it never reboots.

At first I thought it was my power supply dying, and I'm not entirely ruling that out. I also have custom cables, so I'm thinking those might not be reliable? I tried the cables that the PSU came with, same issue. My only other thought is that, for some reason, a voltage setting might be wrong in the BIOS. I don't want to play with that yet, though.

Any ideas? I've never run into this problem before. Usually if I have a bad/failing PSU, the computer would struggle to stay on, especially under a heavy load like RTX gaming.

 

[Lutfij]

Welcome to the forums, newcomer!

Phanteks 1000w Gold-Rated PSU
How old is the PSU in your build? With an RTX 3090, you're advised to work with a 1.2KW or higher PSU. As for your build, was it powering another GPU prior to the RTX3090?

 

[Timmah200]

Phanteks 1000w Gold-Rated PSU
How old is the PSU in your build? With an RTX 3090, you're advised to work with a 1.2KW or higher PSU. As for your build, was it powering another GPU prior to the RTX3090?

PSU was brand new out of the box; it wasn't powering another GPU prior to the 3090...brand new build at the time.
Hmmm....for some reason I figured 1K would be enough. So maybe a higher wattage PSU? Perhaps the initial boot cycle is too much for the PSU to handle? Because under load, I can game at 4K for hours and never have a power issue.

Thank you for the input!