Using APC causes my computer to crash

[Anonymous user]

Hi. I'm having a weird problem and would like some pointers on what to do.

I have PC with Thermaltake Purepower 500w power supply running Windows XP SP3 and APC Back-UPS ES 550VA. Below is what I'm experiencing.

- If I connect the PC to the APC (port with battery backup), the PC seems to experience either sudden reboot or blue screen. It may occur after few days or few minutes that the PC has been up. Doing power heavy work like playing games and encoding seems to make no difference. The crash usually occurs when PC is used normally with minimum CPU load.

- After the crash occurs, the PC is often not able to boot into Windows XP for some time, like it needs to cool down from something. During the boot up after Windows XP splash screen, it would just stall with black screen or get blue screen. If I keep the PC disconnected from the APC for about an hour, the computer is again able to boot into Windows XP like nothing happened.

- If I connect the PC to standard power-strip (not connected to the APC), I do not have these crashes or reboots and I am able to keep the PC on for 1-2 months at a time before any rebooting as would expect. However, after experiencing the crashes as described above by using the APC, the PC still needs to be turned off for about an hour before the PC can boot into Windows XP even connected to standard power-strip.

- I picked up brand new APC Back-UPS ES 550VA recently, and problem is the same. So it doesn't appear to be defective APC.

So based on the above symptoms, my guess is that if the PC is connected to APC, it causes some kind of overheating/stressing of the power-supply somehow until the PC crashes.

Also testing the APC from power loss works fine and battery can keep the PC running for over 15 minutes.

What should I do to fix the problem? I'm thinking that power supply may be the problem, but I don't think I can get the warranty to get it replaced with the weird symptoms I'm seeing. Should I just get a different model of power supply? Could it be due to some other factor?

Thanks.

[Erasmus_apc · Accepted solution]

Did either UPS display a "Site Wiring Fault" (red LED on the side of the unit) at any time? Was the Back-UPS plugged into a wall outlet or daisy chained to a surge strip?

Did either UPS exhibit any beeping sounds or flashing LEDs when these issues occur?

Have you noticed any other power issues with other devices in the room/building?

How old are the UPS'? Serial numbers will tell us.

This power supply, based on specs on Google, does not appear to be Active PFC although this is neither confirmed or denied from what I found. If the power supply is active PFC, this could have something to do with the behavior if power were to suddenly be cut from the UPS and then restored. This could be cause the power supply (assuming active PFC) to "freak" or basically cut off seeing such an odd incoming power signal. The Back-UPS series produces a stepped approximation to a sine wave that is generally not a good match to use with active PFC supplies. You said that it supported it for 15 minutes, which clearly means that either the supply is not active PFC, or it is a supply that is calibrated/manufactured with enough tolerance to be mostly friendly with our Back-UPS unit. A Back-UPS going from on battery to online quickly, however, would send a very sudden stepped sine wave signal (maybe a few AC cycles, maybe several milliseconds, who knows), then back to normal AC power, and it is really hard to rule out the possibility that this is causing an issue.