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Help--homebuilt computer stopped working
I built my son a computer last May, using an Asus IS7 mobo and P4/2.8. For
Christmas I got him new memory, so it's now running 1 GB Dual-channel DDR400 as two sticks of 512. Sometime overnight the computer stopped working. It was idling unattended at the time; he was down the street at a New Year's party. When we hit the power switch, the case and processor fans start running and LEDs come on, but there is no signal to the monitor and the USB Microsoft Optical Wheel Mouse doesn't light. There are NO beeps. I removed and reseated the DVD burner, memory and processor (and replaced the heatsink putty) with no change whatever. The only physical symptom is that the fan over the Northbridge chip is running at irregular speed, as if a bearing were going bad. This is the first computer I've seen that even had a fan over the Northbridge, but I'm assuming, since it's there, it must be needed. Any suggestions? Thanks, -- P. |
#2
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Help--homebuilt computer stopped working
On Sun, 01 Jan 2006 20:23:52 +0000, Pelysma thoughtfully wrote:
I built my son a computer last May, using an Asus IS7 mobo and P4/2.8. For Christmas I got him new memory, so it's now running 1 GB Dual-channel DDR400 as two sticks of 512. Sometime overnight the computer stopped working. It was idling unattended at the time; he was down the street at a New Year's party. When we hit the power switch, the case and processor fans start running and LEDs come on, but there is no signal to the monitor and the USB Microsoft Optical Wheel Mouse doesn't light. There are NO beeps. I removed and reseated the DVD burner, memory and processor (and replaced the heatsink putty) with no change whatever. The only physical symptom is that the fan over the Northbridge chip is running at irregular speed, as if a bearing were going bad. This is the first computer I've seen that even had a fan over the Northbridge, but I'm assuming, since it's there, it must be needed. Any suggestions? Thanks, psu ? |
#3
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Help--homebuilt computer stopped working
"jaster" wrote in message t... On Sun, 01 Jan 2006 20:23:52 +0000, Pelysma thoughtfully wrote: I built my son a computer last May, using an Asus IS7 mobo and P4/2.8. For Christmas I got him new memory, so it's now running 1 GB Dual-channel DDR400 as two sticks of 512. Sometime overnight the computer stopped working. It was idling unattended at the time; he was down the street at a New Year's party. When we hit the power switch, the case and processor fans start running and LEDs come on, but there is no signal to the monitor and the USB Microsoft Optical Wheel Mouse doesn't light. There are NO beeps. I removed and reseated the DVD burner, memory and processor (and replaced the heatsink putty) with no change whatever. The only physical symptom is that the fan over the Northbridge chip is running at irregular speed, as if a bearing were going bad. This is the first computer I've seen that even had a fan over the Northbridge, but I'm assuming, since it's there, it must be needed. Any suggestions? Thanks, psu ? Not unless one of the 12v supplementary wires just blinked out. Are there fuses in there? Since things light up and fans run, the psu isn't completely dead. I will find a way to test the four-conductor line that goes to the CPU, though. Unfortunately, I don't have a meter close at hand, but it's worth checking out. Thanks, -- P. |
#4
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Help--homebuilt computer stopped working
Apparently your motherboard has died. Time for a replacement.
-- DaveW ---------------- "Pelysma" wrote in message news:sTWtf.42$cN4.10@trnddc07... I built my son a computer last May, using an Asus IS7 mobo and P4/2.8. For Christmas I got him new memory, so it's now running 1 GB Dual-channel DDR400 as two sticks of 512. Sometime overnight the computer stopped working. It was idling unattended at the time; he was down the street at a New Year's party. When we hit the power switch, the case and processor fans start running and LEDs come on, but there is no signal to the monitor and the USB Microsoft Optical Wheel Mouse doesn't light. There are NO beeps. I removed and reseated the DVD burner, memory and processor (and replaced the heatsink putty) with no change whatever. The only physical symptom is that the fan over the Northbridge chip is running at irregular speed, as if a bearing were going bad. This is the first computer I've seen that even had a fan over the Northbridge, but I'm assuming, since it's there, it must be needed. Any suggestions? Thanks, -- P. |
#5
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Help--homebuilt computer stopped working
Pelysma wrote: I built my son a computer last May, using an Asus IS7 mobo and P4/2.8. For Christmas I got him new memory, so it's now running 1 GB Dual-channel DDR400 as two sticks of 512. Sometime overnight the computer stopped working. It was idling unattended at the time; he was down the street at a New Year's party. When we hit the power switch, the case and processor fans start running and LEDs come on, but there is no signal to the monitor and the USB Microsoft Optical Wheel Mouse doesn't light. There are NO beeps. I removed and reseated the DVD burner, memory and processor (and replaced the heatsink putty) with no change whatever. The only physical symptom is that the fan over the Northbridge chip is running at irregular speed, as if a bearing were going bad. Is it possible that the mobo was very, very shorted all along, and installing the new memory shifted it around just enough to finally make the short really bad? This can happen around the mounting points and at the corners. I've found that even tiny, insignificant changes in voltage can cause audible changes in fan noise. Still, I would first try another power supply or measure the voltages coming out of the one in there now with a digital multimeter. Any cheapo $3-15 meter is more than accurate enough, provided that it's digital. Sometimes a PSU will work partially and put out only some of its three main voltages That happened to mine after a friend plugged a DIMM in backwards and blew the +3.3V rail. Also try measuring the CPU, memory, and AGP power voltages, although that requires finding the transistors or chips that have those voltages on them. The AGP and memory voltage regulators are near their respective devices and are probably 3-terminal chips (2-3 pins on one side and a metal tab on the other). The CPU voltage regulator is the big one, usually with 1-3 donut coils, several cylindrical capacitors, and anywhere from 2-6 MOSFETs. The CPU voltage is on the metal tab of at least one of those MOSFETs. Don't let your meter probe slip and short something. |
#6
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Help--homebuilt computer stopped working
"larry moe 'n curly" wrote in message
oups.com... Is it possible that the mobo was very, very shorted all along, and installing the new memory shifted it around just enough to finally make the short really bad? This can happen around the mounting points and at the corners. I want to thank you for your comprehensive answer. Unfortunately, I don't have a meter in the house at the moment, and I'm going to have to rustle one up; I guess this is a good excuse to finally invest in one. Previously, as a community college student, I used the ones in the labs. Three possibilities present themselves: the Northbridge fan isn't good, so that chipset might have fried; the PSU, which is ample (450 watts) and not very old, nevertheless might have stopped delivering 12v to the additional 4-conductor connector for the P4 CPU; and fan sensors might have told the BIOS to shut down. I also want to try putting his original single DIMM back in, but it makes me cry because that one is running in my Dell at the moment, and I'll have to shut down the family machine to experiment with my son's game machine. I strongly doubt that the mobo is shorted at the mounting points; I put it in myself, and used quite a lot of care and some nice little nylon washers to minimize that possibility. However, it's worth looking it over. Thanks again for taking the time to answer. -- P. |
#7
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Help--homebuilt computer stopped working
Pelysma wrote: "larry moe 'n curly" wrote in message oups.com... Three possibilities present themselves: the Northbridge fan isn't good, so that chipset might have fried; the PSU, which is ample (450 watts) and not very old, nevertheless might have stopped delivering 12v to the additional 4-conductor connector for the P4 CPU; and fan sensors might have told the BIOS to shut down. I also want to try putting his original single DIMM back in, but it makes me cry because that one is running in my Dell at the moment, and I'll have to shut down the family machine to experiment with my son's game machine. I strongly doubt that the mobo is shorted at the mounting points; I put it in myself, and used quite a lot of care and some nice little nylon washers to minimize that possibility. However, it's worth looking it over. Did you install the washers on both top and bottom of each hole? Also I've found that mobos and cases can flex a lot, sometimes enough to touch one another, so I make it a point to support the mobo within 1" of each corner, even if that means attaching stick-on rubber feet to the case. My guess is that if the northbridge has a substantial heatsink on it in addition to the fan, it didn't fry but could have let the chip get hot enough to make operation unreliable. A have a budget Asus (Asrock) with a fanless northbridge, but the heatsink extends about 1.5" above the chip. What kind of 450W PSU is it? Because if it looks more like this: http://static.flickr.com/43/73954319_bc8f9de6d0.jpg rather than this: http://static.flickr.com/28/67715167_9880b9e1c4.jpg then it can't be trusted, even though your son's computer probably draws only 200-250W. One expert damaged two 500W Powmax Assassin PSUs at loads of just 265W and 277W, but he managed to get 500W out of a Fortron-Source (AKA Sparkle, Hi-Q, PowerQ) rated for just 300W. BTW the PSU in the first link is rated for 580W, the second one for 200W -- that's how much PSU quality varies. |
#8
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Help--homebuilt computer stopped working
"larry moe 'n curly" wrote in message
oups.com... Pelysma wrote: "larry moe 'n curly" wrote in message oups.com... Three possibilities present themselves: the Northbridge fan isn't good, so that chipset might have fried; the PSU, which is ample (450 watts) and not very old, nevertheless might have stopped delivering 12v to the additional 4-conductor connector for the P4 CPU; and fan sensors might have told the BIOS to shut down. I also want to try putting his original single DIMM back in, but it makes me cry because that one is running in my Dell at the moment, and I'll have to shut down the family machine to experiment with my son's game machine. I strongly doubt that the mobo is shorted at the mounting points; I put it in myself, and used quite a lot of care and some nice little nylon washers to minimize that possibility. However, it's worth looking it over. Did you install the washers on both top and bottom of each hole? Also I've found that mobos and cases can flex a lot, sometimes enough to touch one another, so I make it a point to support the mobo within 1" of each corner, even if that means attaching stick-on rubber feet to the case. My guess is that if the northbridge has a substantial heatsink on it in addition to the fan, it didn't fry but could have let the chip get hot enough to make operation unreliable. A have a budget Asus (Asrock) with a fanless northbridge, but the heatsink extends about 1.5" above the chip. What kind of 450W PSU is it? Because if it looks more like this: http://static.flickr.com/43/73954319_bc8f9de6d0.jpg rather than this: http://static.flickr.com/28/67715167_9880b9e1c4.jpg then it can't be trusted, even though your son's computer probably draws only 200-250W. One expert damaged two 500W Powmax Assassin PSUs at loads of just 265W and 277W, but he managed to get 500W out of a Fortron-Source (AKA Sparkle, Hi-Q, PowerQ) rated for just 300W. BTW the PSU in the first link is rated for 580W, the second one for 200W -- that's how much PSU quality varies. Well, it looks more like the second than the first, but I also made an error earlier: it's 350w, not 450w, as I ended up using the Antec psu that came with the case instead of buying the one I was looking at. Might have to go back and get it now... But I can't find a dead wire, either. The voltages on the PSU cables themselves are as advertised. The MOSFETs you mentioned are as follows: Two at bottom end of RAM slots, 3.28v each; one at corner of PCI bus, 2.38v; one next to AGP slot, 1.06v; two next to CPU, 1.17v each. The memory sticks work in my Dell (this one) but I haven't had the guts to try the CPU; don't even know if it has the same number of pins. Messing that deeply with the best working computer in the house when I seem to have fritzed one out is a scary thought. Thanks for your input. -- P. |
#9
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Help--homebuilt computer stopped working
Pelysma wrote: The voltages on the PSU cables themselves are as advertised. The MOSFETs you mentioned are as follows: Two at bottom end of RAM slots, 3.28v each; one at corner of PCI bus, 2.38v; one next to AGP slot, 1.06v; two next to CPU, 1.17v each. The memory sticks work in my Dell (this one) but I haven't had the guts to try the CPU; don't even know if it has the same number of pins. I hate to say it, but I'm afraid your initial diagnosis of a fried north bridge is correct. This is why I don't trust fans, especially the really small ones, which seem to fail the most. On any replacement mobo,. I'd replace any north bridge fan with a heatsink large enough to keep that chip from frying even in case of fan failure. |
#10
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Help--homebuilt computer stopped working
"larry moe 'n curly" wrote in message oups.com... Pelysma wrote: The voltages on the PSU cables themselves are as advertised. The MOSFETs you mentioned are as follows: Two at bottom end of RAM slots, 3.28v each; one at corner of PCI bus, 2.38v; one next to AGP slot, 1.06v; two next to CPU, 1.17v each. The memory sticks work in my Dell (this one) but I haven't had the guts to try the CPU; don't even know if it has the same number of pins. I hate to say it, but I'm afraid your initial diagnosis of a fried north bridge is correct. This is why I don't trust fans, especially the really small ones, which seem to fail the most. On any replacement mobo,. I'd replace any north bridge fan with a heatsink large enough to keep that chip from frying even in case of fan failure. Well, we're just about out of the woods here. I replaced the motherboard with an Asus P4P800-VM, and it POSTs. As I write this, I'm in the last stages of hooking things up. I think I've found the problem on the Abit board, too. There's a visible blister on a small standing capacitor right next to the BIOS chip. Without really knowing, that seems to make perfect sense. He plays a game online called Pop-Cap all the time... -- P. |
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