I'm going to try to make this a thorough as possible, and hope that you can help me narrow down the bad part. I've spent many hours researching this topic, going through trouble-shooting flow charts, and looking over people in similar predicaments. I'll say now that I feel that I've got it narrowed down to either the CPU, or Motherboard. Here we go.
I built for my brother a computer consisting of the following:
Core i5 quad (Stock HS/F)
2 x 2gb Patriot 1333
Evga 9800GTX+ 512mb
BFG 800 Watt Sli-Compatible (Cannot remember exact model)--this was the first PSU.
Gigabyte GA-P55-UD3 (Rev. 2.0)
The computer was running fine for about a month since being built. Then, after a storm hit, the computer went into endless reboot cycles, no post, etc. (My brother was at work; when he came home later that evening, it was doing what was described) Power surge right? Well, here's the weird part.
First, he goes and returns his 9800GTX+ at Fry's Electronics for a brand new one. Doesn't change anything. Then he buys a new PSU (this one being a Thermaltake TR2 RX 650W). Nothing. Then he goes into a computer repair shop, who says the motherboard wasn't seated properly (my bad, but I was suspicious--why all of the sudden does it just short and after a storm...? My knowledge of electronics is far inferior to just putting together a computer, though). So he replaces the motherboard with the same make and model, "properly seated," and it turns on!...
... But only for a week (no storms during this period, plus he invested in an expensive surge protector). Now there are a few things to be aware of. First, this is an older house, built in around the 50's-60's (I don't live there). The wiring in the house is apparently pretty peculiar. Both my dad (a handyman), and a hired electrician said something was "strange" with the house's wiring. First, my dad said it was peculiar the house was receiving 3 Phase power (we're from east coast; out here in Arizona, maybe that's standard?). Second, it seemed there were polarity issues with the socket his computer was plugged into. My dad said the socket appeared to be wired with a ground, but voltage readings seemed erratic, and sometimes it looked as if the the ground was acting as the neutral. Again, I know next to nothing on electronics--just relaying info on.
My brother has now bought a laptop, and his girlfriend uses an iMac in a separate room. No issues have arisen with these devices.
So again, the computer turns on--and by turns on, I mean the disc drives spin up, the LED fans turn on, the motherboard pwr light goes on--then it shuts off within 3 seconds. Reboots after another 3-5 seconds, and repeats.
I have also attempted to do the following:
- Breadboard the motherboard
- Reseat RAM, swap RAM slots, take each RAM out, and take all RAM out - no beeps, same thing.
- Taken out Video Card - also mixed with the previous tests.
- Clearing CMOS by removing battery for ~1 minute
- Removed HS/F, took out processor, and reseated it, and then reapplied Arctic Silver 5 (after using alcohol to remove previous mat.)
- I have tried unplugging all peripherals--while breadboarded--except for motherboard 24pin power, and HS/F &CPU power. No Beeps without any RAM inserted. Also removed processor 8pin power--No beeps. Yes, speaker is plugged in.
- Tested computer with yet another PSU I had lying around for kicks (450 watt, but still)--same symptoms.
On an irregular basis, the computer remains on--it does not keep rebooting. There even appears to be hard-drive activity, but no video, no sound, no beeps, nothing else. Again, this rarely happens.
So 2 graphics cards later, 1 mother board later, 1 PSU later, we're stumped. The only thing that hasn't been replaced is the RAM, the HDD (?), and the CPU.
My initial thought is that the CPU is the culprit, having never been replaced. But first, why would this system work for a week after replacing the motherboard--then die out again? Can the CPU possibly fry the motherboard in some way, and after some period of time? Alternatively, I've heard no beeps may indicate the motherboard is bad. But again, what caused the second one to go bad in the first place?
If you need any other information, let me know.
Thanks a lot,
Edited by lennybird, 13 April 2011 - 10:02 PM.