Question Can a PSU be so bad it fails to power a PCIe X1 slot?

[ppq]

Hello! It's been forever since I've posted on forums, but I have a peculiar situation I can't figure out myself.

A friend of mine brought me a cheap PC he wants to setup for his kid and needs a Wi-Fi network card installed but the card refuses to work. The card is just dead, not detected by the motherboard, not showing up in lspci results in Linux nor device manager in Windows. I've updated the BIOS, tried different PCIe slots, even x16 one, tried setting up PCIe slots to different gens in BIOS – nothing worked. The card is brand new and I know it works, because I've tested it in my PC and it worked fine.

Now, this PC has some random PSU that looks like it came back from the 2000s, so as a last resort, I've decided to swap it with my old be-quiet I had laying around and everything started working! I even put in my old GTX970 for good measure and it worked with no issues.

Ok, so the PSU sucks obviously, but I'm trying to understand this issue beyond "terrible PSU". How is this possible that this PSU can sustain this system with full load just fine, but won't power a PCIe X1 card at idle? It just doesn't make sense to me. Isn't the 12V for CPU and PCIe coming from the same line? I've tried measuring the voltages and confirmed there is 12V on every yellow wire. I can't test this PSU with my GTX970, because it doesn't even have any PCIe wires, just 4pin CPU, yet it claims 500W. How terrible a PSU would have to be to fail powering a Ryzen 3 2200G, 2 fans, single SSD and a network card?

I've been told this is a second PSU in this computer, since the previous one burned down, so there is a possibility something got damaged when that happened, but why would it work with my PSU just fine? I've tried the exact same config with just 4pin CPU connected and the network card worked fine, swapped back the PSU and it's dead again, yet the system can sustain Prime95 and Furmark running at the same time.

The system in question:
Motherboard: GA-A320M-S2H Rev 1.1
CPU: Ryzen 3 2200G
PSU: Akyga AK-B1-500E (I have no idea what is this, some local cheap brand or something)
Network card: PCE-AX3000

 

[Lutfij]

Welcome to the forums, newcomer!

PSU: Akyga AK-B1-500E (I have no idea what is this, some local cheap brand or something)
Yes it's horrible. I would replace the unit with something that's reliably built, with a 450W unit, if you're not interested in dropping a discrete that's more than mid-tier. Where are you located? What is your budget for a PSU purchase? Preferred site for purchase? What is the make and mode of your case?

Ok, so the PSU sucks obviously, but I'm trying to understand this issue beyond "terrible PSU".
It's horrible, you're wasting time trying to dissect something that's not worth it's time.

I've been told this is a second PSU in this computer, since the previous one burned down, so there is a possibility something got damaged when that happened, but why would it work with my PSU just fine?
It's also possible that the prior PSU knocked out the motherboard, if that's possible, then the next thing that'll happen is intermittent failures and anomalies with your components or the platform overall.

 

[ppq]

I'm aware this PSU belongs in a landfill. I've already told the guy it has to go regardless if it works or not.

What is your budget for a PSU purchase? Preferred site for purchase? What is the make and mode of your case?
I just put together a nice gaming rig for his older kid, so he is short on cash right now and just wants this one to work. I was thinking an MSI A550BN could be a good value and provide some headroom for a discrete GPU once his kid asks for something more than [game name I can't type, because I'm being roblocked by the spam filter].

As for the case, it is just some no name box of quality so excellent a good cardboard is sturdier than this thing, but there's no budget for anything else unfortunately, so it has to do for now.

It's horrible, you're wasting time trying to dissect something that's not worth it's time.
It's just my curiosity at play. Figured someone out there may have some ATX power circuitry knowledge to share, but I'm aware that "junk PSU magic" may be the eventual answer

 

[USAFRet]

but there's no budget for anything else unfortunately, so it has to do for now.

And running it may indeed kill the other parts.

I personally have had a dying/cheap PSU kill the motherboard.

 

[NightHawkRMX]

Perhaps the PSUs voltage or ripple is going out of spec, and the board has enough smoothing caps on the VRM that its able to run stable, but the wifi card is too sensitive.
This is just a guess, but in any case, if the system has no issues with the bequiet PSU but it won't work with the current PSU, the solution seems fairly simple to me. Regardless of what exact characteristic of the power output is inadaquate, the PSU is inadaquate and needs replaced. Honestly, even if the system was working 100% fine, the PSU needs to be replaced for safety concerns.

 

[NightHawkRMX]

I was thinking an MSI A550BN could be a good value and provide some headroom for a discrete GPU

These are reasonably decent budget units. Would be a good upgrade.

Cases are whatever. Its the one area where cheaping out is usually okay for a system like this. Airflow is a lot less of a concern here with a basic CPU and no dgpu than it would be in other systems