Power Issues

I am having a frustrating problem.
I built a new desktop recently (Feb-ish) in my dorm. Its a:

950W Corsair PSU
Phenom XII 720 BE
HD 4860
HT Omega Claro Halo
2x WD 600GB Black (R 0)
4x2GB GSkill DDR3
with a ZeroTherm NV720 on the cpu

The case has 3x 140mm led fans and 1x 120mm (that lian li offbrand, dragonlord?). Problem is, when I brought it home for the summer, whenever the A/C is on, it keeps randomly powering off. Its an instant shutdown, no warning, beep, or bsod, like someone yanks the plug. This happens only in the evening. It can run all day with the AC on, but in the evening/night, It begins the random power kills.

I have tried:

>>Removing every component from the motherboard except PSU, cpu, and ram, all at factory settings. no fans (except cpu), no cards, no HDDs, no speakers, monitor, mouse, blah blah, everything gone. I ran it in the bios menu, and after 1/2 hr it cut out. again, its completely random, so its hard to diagnose/reproduce conditions. There are 2 other desktops that run perfectly fine, though they are probably only doing about 250W each.

>>I bought a $170 APC UPS rated for ~900W, even though my PC only pulls ~370W when gaming, sub 200W when idle in bios with all components removed (see above). I got it for upgrade-ability. This UPS should not only plow through blackouts, but has built in voltage regulators so if my voltage drops suddenly (ie a brownout type event), It should have no effect. I am not having brown outs, so any voltage issue is unnoticeable around the house. There has been no noticeable effect on my random power offs, either.

>>I have plugged into every outlet in the room, as well as getting a utility extension cable from my shop and running it to outlets in other rooms. Still cuts out.

>>I am overclocking my cpu, as well as unlocking it (i got a lucky one), but that was the first obvious cause i thought of so Ive reset to factory defaults for the time being. It is not overheating, none of the temp monitors say anything, and my hand on the heatsink dont feel very warm. graphics card is a tad warm, but nothing not ordinary. I have re-greased all my heatsinks (graphic and cpu) and reset them.

>>Shutting off almost everything in the house (except A/C), like TVs, appliances, other computers, lights.

>>and random combinations of all the above.

Like I said, It ran perfectly almost 24/7 (on in the morning, off when i went to bed late at night) in my dorm, but no go at home. So, if anyone has had this problem, or has any suggestions, I'm ready to make this problem go away. The computer is not much fun when you know that any second it could shut off.

Sorry for the novel
3 answers Last reply
More about power issues
  1. It sounds more like your dorm room doesn't have a proper AC power flow, you should probably tell your landlord, or who ever is in charge of your dorm. The fact that its consistent in the evening means that it is not the hardware. For a solution, try a different plug.
  2. Well I ran into something many years ago, a woman bought a computer at my shop and would return claiming it would shut down. We invited her to sit at the computer and try and duplicate the problem, she couldn't. This went on about four times before I finally asked her about her house. Her grandfather had built it in 1904,,, I suggested she have the power co. come out and check her lines. What they found out was due to the aged wiring the voltage would fluctuate frequently to about 104v AC. If it drops below 109v AC you can expect problems, also if illegally wired, too many lines used the wire heats up causing resistance which drops the voltage.
    Now what was your problem, I forgot?
  3. Haha, like I said, sorry for the novel.

    I figured that, it is indeed and older house, but I would have thought a ups would solve such issues. I've also watched the voltage input on the ups lcd, and it hovers at 120V, +/- 2V. But that could mean anything, and I don't know the sample frequency. Without a multimeter, I guess I won't know.

    What really gets me is the reliance on a certain time of day. Also not to mention the 2 other desktops and home theater that operate without any issues at all.

    ~2 years later edit: Just in case someone stumbles across this thread with a similar problem, our house was not grounded properly. It was causing the electronics to do whacky things, it's just that the other computers where at such lower power draws, it didn't affect them like it did mine. It ended up damaging my power supply, so I had to swap it out after we moved. All problems gone, it's been running without issue for a couple years now. Highly recommend the Corsair PSUs :)
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