- May 19, 2011
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A computer I built about ten years ago for a customer was having problems booting: the computer would power on, then within a split second back off, then about a second later it would switch back on but not POST, no display either. The customer had switched the computer and monitor off at the wall socket before my arrival.
What followed was a bit of a clown car of symptoms and theories. For example early on I thought that I'd have to dive inside the case, maybe try a spare PSU, that kind of thing, but when I turned the PC on its side I noticed that the customer had a keyboard/mouse receiver plugged in the front as well as an older one plugged in the back. I unplugged both and out of curiosity I switched the machine on. It came on almost completely fine except the display didn't come on, but the HDD LED was flickering consistent with the OS booting and the Windows startup sound came through the external speakers. I shut it down, plugged the correct receiver in the back of the PC, started it back up again, and the display came on.
At this point I'm wondering if some wacky compatibility issue with two wireless receivers was coming into play, and my decision to plug the receiver in the back was based on experience of "not all USB ports are created equal" (ie. front panel USB vs board-mounted USB). I power cycled the computer a couple more times, no problem, stood the computer tower-style as its design intended, power cycled a few more times, problem apparently solved? As the wireless receiver wasn't receiving particularly well in the back, I returned it to the front socket, power cycled a few more times, no problem.
I wasn't particularly satisfied that a "new" wireless receiver (allegedly a year old) could cause the original problem, or say some transient power issue had confused the PSU because the computer was fully-off when I arrived, but I had to respect the fact that symptoms had subsided, and also respect the fact that sometimes I don't have a good and sound explanation for cause and its logical resolution. If it works it works.
I was chatting with the customer and helping fix some mild issues on their laptop when I thought I'd give the computer another round of testing. The problem reoccurred. I faffed around a bit more with half-baked theories such as the wireless keyb/mouse receiver or that I needed to leave the computer off for a bit before each test, then decided to move on to the PSU. I turned the computer on its side, then out of curiosity I booted it again and it did exactly the same thing as it did the first time it recovered: Windows booted, no display, power cycle, display OK. At this point I decided that if leaving the computer off for a bit is a relevant factor in testing then I'm better off taking the computer home. I took the customer's wireless USB adapter with me just in case it was relevant but not the keyboard/mouse/receiver.
At home I plugged the computer in, switched it on, original problem occurred. I turned the computer on its side, and before I got started in testing I thought I'd try to boot it again. It POSTed and OS booted minus the display again, then a power cycle later it started properly. Instead of faffing around with anything else at this point, I tested it a good 5 or 6 times with 5-minute gaps between, it booted every time. Then I turned it right way up. Original problem occurred again. wth.
It was at this point I threw a PC speaker into the mix. Immediately it cited RAM. I ran the test again, same beep code.
I'm cursing the fact that the case I used before this one had an in-built speaker and this one didn't. I'm also cursing the fact that I brought a PC speaker with me for the same reason I brought a spare monitor and PSU, but because I got caught up in the red herring symptoms I didn't try it on-site.
I've started by reseating the RAM which seems to have done the trick so far, and I guess that testing the PC at home is more beneficial as I can run extended testing without charging for 'waiting' time.
TLDR: always have the internal PC speaker plugged in when testing a PC that won't boot. Potentially saves lots of time.
What followed was a bit of a clown car of symptoms and theories. For example early on I thought that I'd have to dive inside the case, maybe try a spare PSU, that kind of thing, but when I turned the PC on its side I noticed that the customer had a keyboard/mouse receiver plugged in the front as well as an older one plugged in the back. I unplugged both and out of curiosity I switched the machine on. It came on almost completely fine except the display didn't come on, but the HDD LED was flickering consistent with the OS booting and the Windows startup sound came through the external speakers. I shut it down, plugged the correct receiver in the back of the PC, started it back up again, and the display came on.
At this point I'm wondering if some wacky compatibility issue with two wireless receivers was coming into play, and my decision to plug the receiver in the back was based on experience of "not all USB ports are created equal" (ie. front panel USB vs board-mounted USB). I power cycled the computer a couple more times, no problem, stood the computer tower-style as its design intended, power cycled a few more times, problem apparently solved? As the wireless receiver wasn't receiving particularly well in the back, I returned it to the front socket, power cycled a few more times, no problem.
I wasn't particularly satisfied that a "new" wireless receiver (allegedly a year old) could cause the original problem, or say some transient power issue had confused the PSU because the computer was fully-off when I arrived, but I had to respect the fact that symptoms had subsided, and also respect the fact that sometimes I don't have a good and sound explanation for cause and its logical resolution. If it works it works.
I was chatting with the customer and helping fix some mild issues on their laptop when I thought I'd give the computer another round of testing. The problem reoccurred. I faffed around a bit more with half-baked theories such as the wireless keyb/mouse receiver or that I needed to leave the computer off for a bit before each test, then decided to move on to the PSU. I turned the computer on its side, then out of curiosity I booted it again and it did exactly the same thing as it did the first time it recovered: Windows booted, no display, power cycle, display OK. At this point I decided that if leaving the computer off for a bit is a relevant factor in testing then I'm better off taking the computer home. I took the customer's wireless USB adapter with me just in case it was relevant but not the keyboard/mouse/receiver.
At home I plugged the computer in, switched it on, original problem occurred. I turned the computer on its side, and before I got started in testing I thought I'd try to boot it again. It POSTed and OS booted minus the display again, then a power cycle later it started properly. Instead of faffing around with anything else at this point, I tested it a good 5 or 6 times with 5-minute gaps between, it booted every time. Then I turned it right way up. Original problem occurred again. wth.
It was at this point I threw a PC speaker into the mix. Immediately it cited RAM. I ran the test again, same beep code.
I'm cursing the fact that the case I used before this one had an in-built speaker and this one didn't. I'm also cursing the fact that I brought a PC speaker with me for the same reason I brought a spare monitor and PSU, but because I got caught up in the red herring symptoms I didn't try it on-site.
I've started by reseating the RAM which seems to have done the trick so far, and I guess that testing the PC at home is more beneficial as I can run extended testing without charging for 'waiting' time.
TLDR: always have the internal PC speaker plugged in when testing a PC that won't boot. Potentially saves lots of time.
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