Question Antect vp700p only powers up with one pc. Wut?

[Lolpingu]

So, I have this antec vp700p which refuses to work with two of my machines, one with a z97-k mobo and one with a ga-ma67-ud2h mobo.
Keep in mind that it worked with the z97-k mobo which had 16gb of ram on it aswell as an i5 4690k and a gtx980ti, and several high rpm case fans, and performed its duties admirably for years, enduring multiple spikes and outages.

A few months back I had to take apart the z97 rig for a while to get my gaming addiction under control. A week ago, I put the old rig together and two more with all the leftover parts from years of pc upgrades. The other two machines have a ga-h67ma-ud2h and a ga-ep43-ud3l.
The vp700p absolutely refuses to work with the former and the asus rig, but works just fine with the ep43 rig.

I have considered the possibility of some but not all of the cables being defective, but the main mobo cable (pci? pce?) evidently works fine and the psu has MANY (oh god, so many) redundant cables that I could use for the mobo power socket. None of them do the trick, including the one I used for the ep43 rig's power socket.

I also considered that the psu's capacity somehow went down over time due to wear (not sure if that's possible), but I tried running the main rig without the gpu and with just one 8gb stick which would take the power draw down far below even the fully built ep43's power draw. Nothing.

Does anyone know what's happening here?

 

[Quarkzquarkz]

What is your wattage for your Power supply? Anything less than 600 over many many years is quite iffy, especially in 2019 where I think the minimum is 600 watts. If you had that PSU over several years it's bound to lose it's capacity, depending on it's rating as well.

If anything just check the warranty most give 5-10 years right off the bat so you can complain that your psu doesn't work. Good luck!

 

[Lolpingu]

What is your wattage for your Power supply? Anything less than 600 over many many years is quite iffy, especially in 2019 where I think the minimum is 600 watts. If you had that PSU over several years it's bound to lose it's capacity, depending on it's rating as well.

If anything just check the warranty most give 5-10 years right off the bat so you can complain that your psu doesn't work. Good luck!

It's rated at 700w.

The thing is, it refuses to work on the two rigs it refuses to work on even if I pull their gpus out, reducing their power draw to the mid 300s at most.

The ep43 rig draws somewhere around the high 400s under load, and the psu has no trouble handling it.

Basically, even if its output has declined over the years, it's AT LEAST good enough to handle those systems without their gpus since it handled a system with higher power draw.

Edit: also, from prior experience with using underpowered power supplies, the pc will usually POST unless there's a staggering difference between what the system needs and what the psu outputs.