Computer won't boot

[larry38]

My daughter's computer (I built this one a few months ago) and it has been running great. This weekend she called to tell me that it wouldn't boot up when she tried to start it in the morning. She says that when she first starts it, it will display the ASUS motherboard splash screen and then the monitor turns black with a flashing straight line about 1/2" long showing in the upper left part of the monitor screen. The computer will not complete the boot. We discussed this on the telephone and tried to get the computer to boot into safe mode by pressing F8 from the beginning. The boot sequence stops at a screen asking to pick the preferred boot device. I thought I might have given her a copy of UBCD when I gave her the new computer so I had her select the first optical device and put that disk into the computer to see if it would boot. Apparently it was not the UBCD disk but a memtest86 program and it started running that software. I had her stop that and somehow we were able to get to the computer to boot into safe mode. I then had her go to a restore point that corresponded to a time when the system was working normally. That appeared to be successful because she said the computer had worked great all weekend. This morning when she turned it on, it stopped during boot-up again stopping at the black screen as before. Does any one have a suggestion?

The computer components are as follows:
PSU - Antec EarthWatts EA650W
CPU - Intel Core i5-750 Lynnfield 2.66 GHz 8MB L3 Cache
Mobo - ASUS P7P55D LGA 1156 Intel P55 ATX Intel motherboard
PAM - Corsair XMS3 4GB (2X2GB)
HDD - WD Caviar black WD7501AALS
Optical drive - LITE-ON Black 24X
Video Card - ASUS EAH4670/DI/1GD3/V2 Radeon HD 4670
All in one card reader - Rosewill RCR-IC001
OS - Windows 7 Home Premium 64 bit

[glc]

Have her run memtest for a couple hours. Then I'd run WD Diags on the hard drive.

[larry38]

OK, I've got her scheduled to run memtest and to download the WD diagnostic software; she will run that after running memtest. I just talked with her and found out that when she gets the black screen the computer is locked up - i.e. it doesn't respond to anything. She turned the computer off and shut the power off to the computer using the power supply switch. After about a minute, she turned the power supply back on and was able to boot the computer with no problems and everything seems to be operating as expected. I found out that what she normally does when she shuts the computer down is to shut it down using the windows procedure (start, turn off computer etc) but she doesn't normally turn off the power supply switch.

After she completes the memtest and WD diagnostics, I'll report back the results tomorrow as she is going to run the extended WD test so she will let it run overnight.

[larry38]

She ran both memtest and the WD Acronis extended test. The computer passed both test with nothing showing up. Does anyone have an idea as to why when the boot-up fails and you start over by pushing the start button for an extended period to stop it and then reboot it continues to stop the boot sequence before the BIOS screen appears (ends with the black screen) but if you turn the power off at the PSU switch and then start over, it reboots with no problem and continues to run with no obvious other problems?

[glc]

Most likely a PSU or motherboard issue.

[larry38]

Thanks, glc, for the ideas re: psus or mobo issues. Any ideas as to where to start looking or should we treat it like many "electronic intermittent failures" and wait for it to fail completely?

[glc]

How far does your daughter live from you? Do you have a spare PSU that is known good for testing purposes?

[larry38]

Unfortunately she is ~300 miles away and doesn't have a spare psu. I have the one I salvaged from her old computer (same specs as shown in my signature as I built both of them at the same time) after it failed. I could send to her and have her put it in if you suggest that might be worth doing. What do you think?

[glc]

Well, you are gonna have to do something, but I don't think that PSU is gonna have an 8 pin CPU connector. Just running it with the 4 pin may not be good enough.

Sounds like an excuse to wangle a Thanksgiving invite to me......

[larry38]

Good idea, but that probably won't happen. I'll look into other possibilities. At the price of another new psu from Newegg, I can't drive there and back so I will probably go that way and they she'll have one for possible future use if it doesn't fix the problem. Thanks again for your help, Larry

[glc]

The power requirements of a 4670 are relatively modest - send her one of these:

Newegg.com - Antec NEO ECO 520C 520W Continuous Power ATX12V v2.3 / EPS12V 80 PLUS Certified Active PFC Power Supply

Can't beat the price with that promo code and rebate, and it's free shipping.