?

Log in

No account? Create an account

Previous Entry | Next Entry

I hate it when computers make no sense

I like fixing broken computers, whether its the software or hardware. I find it intrinsically enjoyable to note the symptoms, list hypotheses, and systematically test fixes until the computer is running again properly.

Except when I run into a problem that seems to make absolutely no sense to me. Yesterday I ran into a wall, the likes of which I haven't seen in the longest time. I'm sparing those with no interest in the continuing saga of Paul's computer with an lj-cut.


To review where I've been, Paul had been complaining about frequent crashes on his computer. We could not even get through a full Ad-Aware search for spyware without a crash. In retrospect, I should have removed the drive, placed it as a slave in another computer, and scanned it that way. But the drive had been suffering for a long time from some unfixable glitches in the XP operating system, so I decided it was time for a new hard drive. Paul could leave his old drive in the computer as a slave to retrieve files.

My standard operating procedure for this fix is to find a bargain WDC drive that is larger than the drive in my own desktop, copy my old drive to the new drive, wipe my old drive clean, and reinstall XP for the computer that needs a new drive. I found a great deal at Best Buy for a 160GB WDC drive, so I began copying the contents of my old 120GB drive to the new one with WDC's Data Lifeguard tools. The Tools have been vastly improved over the last five years, and things were going very smoothly.

Then we had the freak thunderstorm that resulted in three blackouts (with brownouts in between) in a period of 10 seconds. This hung my computer and made both drives unbootable. I had no choice but install XP from the CD. I did this on the 160GB drive, which I found actually contained almost all of the files on the old drive because the copying process had almost completed before the storm. Of course almost none of the old programs ran, so there was a lot of reinstalling to do. But that's a side issue. Back to Paul's computer. I deleted almost everything from the 120GB drive and prepared to reinstall XP on it in Paul's computer so that all of the hardware would be detected.

When I hooked up the hard drive in Paul's case and attempted to boot from the XP CD, the power supply unit flashed on for half a second but would not start the system. I figured, bad power supply unit, and bought a new one (430 instead of 350 watts) from Best Buy and tried again. Same thing.

Next step, new motherboard. I ordered the same board (MSI K7N2) and it arrived yesterday. I found that it is actually a slightly updated version of the board, with SATA support. The locations of some part were also slightly different. So, I installed the new board and plugged everything in. I actually made a slight mistake the first time, and I hope this didn't cause damage. The ATX power supply had a 24-pin plug, the last 4 pins of which are detachable for motherboards (such as the K7N2) that take a 20-pin connector. My mistake was plugging the remaining 4 pins into the 12V CPU socket. I did not realize there was a separate cable for that socket. So, at first, nothing powered up. When I corrected my mistake, everything did power up--except the CPU fan. So, I tried the old power supply unit, and everything started up! I booted from the CD and began installing XP on the 120GB drive.

Then the mysteries began. I left the room briefly and when I came back I found that the monitor screen was totally dark. I could not tell if the install was still going on, so I shut the computer down. When I tried to restart, the monitor presented a "no signal" message. So, I took the AGP video card out and installed an old VGA card in a PCI slot. The system booted fine and actually continued with the XP install! However, the install got to the screen where you are given options to set the time zone and so forth, and it requires clicking a Next button to do so. But the system was unresponsive to the keyboard and mouse (which had been functioning fine earlier in the set-up). The system seemed frozen. I decided to restart with a PS2 keyboard and mouse instead of the wireless USB keyboard and mouse in Paul's system.

But now the monitor again indicated it was not receiving a video signal. I tried various video cards and even another monitor to no avail. At one point I got the system going again by putting the VGA video card in another PCI slot, but when the XP install process tried to resume, it reported an error and said I had to start the reinstall from the beginning. When I tried, again the monitor said no signal.

Now I am thinking there might be a problem with the processor. As it happened, I had another Socket 462 CPU in my own desktop, so I replaced Paul's with mine. No luck. At this point I got a phone call from my son, Martin, and I described the computer problem to him. He suggested trying new memory, as that was the only thing I had not replaced. So I took the memory out of my own desktop and installed in in Paul's computer. Still the problem with no video signal. I noticed that in one of the AGP video cards I tried, the built-in fan would not even spin up on boot. Maybe the PCI slots are getting only intermittent power? How could that be? It is awfully hard to troubleshoot when you have no video to see what is going on.

What does not make sense to me is that I have essentially rebuilt this computer with parts that are either new or had been confirmed as working in my own desktop:
brand new motherboard
brand new power supply unit (which did not work, but the old one did)
previously working hard drive
previously working CPU
previously working memory
4 different video cards

I tried booting with the bare minimum of connected peripherals, using only the above components, but keep getting this intermittent video signal failure. What the heck to do?

I'm considering buying a completely built system and modifying it, but I really hate to go that route. What bugs me is that I know that even though the system failure does not make sense to me, there IS a reason, and if I could figure that out I could fix it. But I can't figure it out!