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Unusual symptoms on dekstop computer

I have a Windows Vista Home pc with strange symptoms. In Windows it goes past the Vista loading status bar screen, then goes to a blank black screen, no cursor or anything. THe monitor signal stays on, but nothing happens, just blank screen.
I tried safe mode, same thing. Tried last known good, same.
I got a vista cd and booted to that next. It gets past the vista status bar loading screen and then hangs on a blank green screen. It stays there indefinitely. I confirmed the cd is fine on another pc.
It has an Asus P5K-E motherboard and standard desktop PSU. I notice the PSU has a slight high pitched noise coming from it when there's power going to it.
Also, the hard drive is sometimes not detected in the bios, and I get 'no boot device found'
I'm thinking it may be the PSU or motherboard, but don't have the luxury of spare parts to test in it.
Any suggestions?

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Lordy123

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JohnnyCanuck

Symptoms are similar to bad capacitors - that's the first thing I'd check. Open your computer and carefully examine the capacitors for bulging tops (they should be perfectly flat) or evidence of leakage at the bottoms. If you have bad caps, they can be replaced if you are handy with a soldering iron. Otherwise you'll have to buy a new motherboard.

Here are some images (right side of page) to help you determine if you have bad capacitors:

http://www.badcaps.net/pages.php?vid=5

BitsBytesandMore

If you have a voltage tester, certainly testing the output of the cables to the hard drive would help narrow this down.

The fact that sometimes it detects the hard drive and other times it doesn't could mean a problem with the PSU but could also just be a bad battery on the motherboard or even a bad motherboard.

Since you can't swap and test parts, I would suggest that you start with the most inexpensive: test the PSU. In this link from Wikipedia you will find all the "expected" values to compare to yours: http://en.wikipedia.org/wiki/Computer_power_supply
I hope this helps.

Bits ...

Line One

ASKER

No evidence of bulging/leaking caps.
Tried booting to cd with hard drive disconnected-and it works. Doing more tests now with other drives

Line One

ASKER

HD failed seagate diagnostics. I had incorrectly ruled it out as possibly faulty when it was hanging booting to cd