Confusing PSU Behavior

[ThiccJesus]

Hi, all.

I recently upgraded my CPU to an AMD 5900x; no issues there. However, I wanted to upgrade my current PSU (750W Bronze) to a more efficient one with higher wattage to give me some headroom in the future. I purchased a new Corsair RM850x 80 Gold modular. Got it home, installed it, and machine will not POST with the new PSU but the power will flicker on for a split second. I double-checked all connections and re-seated them. Same result.
 

I have sleeved cable extensions, but thinking they might be causing an issue, I took them out of the equation and used only the cables that came with the RM850x unit. Still no POST but same power flicker. I cannot find anything online that says there are compatibility issues with my hardware.

 

Other than a bad PSU (seems unlikely), is there something else that could be the issue? Mobo is ASRock X570 Pro4 BIOS P4.50. Other than the essential hardware, I have a secondary 2.5" SSD connected to the PSU. Am I missing something?

[BlueChinchillaEatingDorito]

3 minutes ago, ThiccJesus said:

Hi, all.

I recently upgraded my CPU to an AMD 5900x; no issues there. However, I wanted to upgrade my current PSU (750W Bronze) to a more efficient one with higher wattage to give me some headroom in the future. I purchased a new Corsair RM850x 80 Gold modular. Got it home, installed it, and machine will not POST with the new PSU but the power will flicker on for a split second. I double-checked all connections and re-seated them. Same result.
 

I have sleeved cable extensions, but thinking they might be causing an issue, I took them out of the equation and used only the cables that came with the RM850x unit. Still no POST but same power flicker. I cannot find anything online that says there are compatibility issues with my hardware.

 

Other than a bad PSU (seems unlikely), is there something else that could be the issue? Mobo is ASRock X570 Pro4 BIOS P4.50. Other than the essential hardware, I have a secondary 2.5" SSD connected to the PSU. Am I missing something?

Sleeved cable extensions... do you mean like replacement modular PSU cables or extensions that plug into the existing Corsair ones. The former would be dangerous as not all PSUs are wired the same at the modular side so you could've fried or shorted something. 

[ThiccJesus]

9 minutes ago, BlueChinchillaEatingDorito said:

Sleeved cable extensions... do you mean like replacement modular PSU cables or extensions that plug into the existing Corsair ones. The former would be dangerous as not all PSUs are wired the same at the modular side so you could've fried or shorted something. 

Extensions that plug into the Corsair ones. Initially, I hooked it up as Corsair PSU > Corsair cables > Sleeved extensions > Mobo. When that didn't work, I took out the sleeved extensions and ran the Corsair cables straight from the PSU to the mobo. Still didn't work.

[BlueChinchillaEatingDorito]

1 hour ago, ThiccJesus said:

Extensions that plug into the Corsair ones. Initially, I hooked it up as Corsair PSU > Corsair cables > Sleeved extensions > Mobo. When that didn't work, I took out the sleeved extensions and ran the Corsair cables straight from the PSU to the mobo. Still didn't work.

Ok ok, good. Was worried there as we've had a few people do the former without checking and ended up with fried hardware. If you switch back to your original PSU, everything is fine? 

[ThiccJesus]

15 minutes ago, BlueChinchillaEatingDorito said:

Ok ok, good. Was worried there as we've had a few people do the former without checking and ended up with fried hardware. If you switch back to your original PSU, everything is fine? 

Yep; everything is fine with the 750W. 

[BlueChinchillaEatingDorito]

On 1/9/2023 at 8:17 PM, ThiccJesus said:

Yep; everything is fine with the 750W. 

I would RMA or get your store to replace it then. Especially if you've just bought the thing. No point trying to troubleshoot further if the old PSU works but the new one doesn't with the same hardware. 

[ThiccJesus]

On 1/11/2023 at 8:28 PM, BlueChinchillaEatingDorito said:

I would RMA or get your store to replace it then. Especially if you've just bought the thing. No point trying to troubleshoot further if the old PSU works but the new one doesn't with the same hardware. 

So, things continue to be confusing as hell. I exchanged the Corsair RM850x for an EVGA 850GT Supernova this morning. Installed it in my machine (no cable extensions; just used stock cables). Same behavior - flicker of power and nothing more. Since I cannot find anything online that would indicate hardware incompatibility, I am thinking that there might be an issue with how my place is wired (strikes me as unlikely, but I'm not an electrician). I tried multiple outlets (only thing in the room that was plugged in was the PC) with no success. Any ideas before I consider taking the machine in to see if Micro Center has the same issues with it to rule out any problems with the machine itself?

 

For what it's worth, here is my current hardware: ASRock X570 Pro4 mobo (BIOS vP4.50), AMD Ryzen 9 5900x CPU, Zotac RTX 2070 Super GPU, 16GB DDR4 RAM, M.2 1TB SSD (boot), 2.5" SSD, and 750W 80 Bronze PSU.