UPS won't switch to battery power with second PC.

[drummerdimitri]

I have two PC's connected to a UPS that I use for mining and they run 24/7.

Problem is one of them is causing me problems. It's not an overload issue seems like something might be up with the PSU since it works fine with the other PC with a 600W heater connected to it.

Could the PSU be behaving strangely for example causing some kind of  power surge back to the UPS when the power cuts out and the UPS protects itself by shutting down instead of switching to battery power?

Could it possibly be the GPU since it doesnt behave this way when I am doing a CPU stress test?

I could go trough the process of elimination but it's taken me a long time to isolate other variables and narrow it down to something with this specific PC.

Any ideas are welcome.

[BradC]

Which UPS? A modified sine wave unit will often cause issues with active PFC power supplies leading to one, the other or both hitting some form of protective shutdown. These issues don't occur with genuine sine wave units.

[drummerdimitri]

Which UPS? A modified sine wave unit will often cause issues with active PFC power supplies leading to one, the other or both hitting some form of protective shutdown. These issues don't occur with genuine sine wave units.

I'm talking about a CyberPower cps1000e.

It outputs a pure sinewave up to 40% load and then turns into a modified sinewave.

That being said however, it can't be an issue of non sinusoidal power since even when powered alone (30% load) it still wont let the UPS transfer to battery mode...