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#1
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Weird Mobo Problem...
I just bought a Shuttle MOBO w/ Athlon 2700+ combo. The problem is that 90% of
the time when I hit the power button, the CPU fan and the MOBO power light up, but I don't even get a post from the mobo. It does this even when I only have the video card hooked up. 10% of the time it does post and boot up normally, but it erases the FSB memory in the BIOS setting, and boots up at 100 Mhz FSB setting. However, if I get into BIOS, it go back to 166 Mhz on reboot even if I don't do anything and just exit. Anyone knows what is causing this? I've exchanged the MOBO and power supply from the place I bought this at, and I switched out the memory, but it still does this...I'm totally stumped... Grativo |
#2
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Are you using high-performance memory by any chance, like Corsair XMS, OCZ,
Mushkin, esp. PC3200? These high-end memory products often require more voltage than the mobo normally provides by default, so it sometimes won't boot. In such cases, you need to increase vDimm a little to make the system bootable. Of course, this can be a catch-22, which is why I always keep some cheap, generic PC2100 lying around, just in case. But this is just speculation, it could be other things, but it's one thing to consider. Also, is this perhaps a "mobile" Athlon processor? Is the PSU a quality unit? What model of mobo? Jim "Grativo" wrote in message ... I just bought a Shuttle MOBO w/ Athlon 2700+ combo. The problem is that 90% of the time when I hit the power button, the CPU fan and the MOBO power light up, but I don't even get a post from the mobo. It does this even when I only have the video card hooked up. 10% of the time it does post and boot up normally, but it erases the FSB memory in the BIOS setting, and boots up at 100 Mhz FSB setting. However, if I get into BIOS, it go back to 166 Mhz on reboot even if I don't do anything and just exit. Anyone knows what is causing this? I've exchanged the MOBO and power supply from the place I bought this at, and I switched out the memory, but it still does this...I'm totally stumped... Grativo |
#3
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Grativo wrote: I just bought a Shuttle MOBO w/ Athlon 2700+ combo. The problem is that 90% of the time when I hit the power button, the CPU fan and the MOBO power light up, but I don't even get a post from the mobo. It does this even when I only have the video card hooked up. 10% of the time it does post and boot up normally, but it erases the FSB memory in the BIOS setting, and boots up at 100 Mhz FSB setting. However, if I get into BIOS, it go back to 166 Mhz on reboot even if I don't do anything and just exit. Anyone knows what is causing this? I've exchanged the MOBO and power supply from the place I bought this at, and I switched out the memory, but it still does this...I'm totally stumped... Grativo What happens if you press the reset button on the computer when it fails to boot with power being turned on? (Leave the power on for this test) There is a lead from the power supply that is used to reset the logic on the MB. If the pulse from the PS does not occur fast enough the MB logic will not reset and consequently not boot the computer. Pressing the RESET button and getting the computer to boot would tend to indicate this is where your problem might reside. Many MBs set the FSB back to their default values when they fail to boot as you describe. That part of the failure is not unusual. |
#4
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#5
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Are you using high-performance memory by any chance, like Corsair XMS, OCZ,
Mushkin, esp. PC3200? I'm using a Kingston pc 2700 and generic PC2700. I don't think this is a memory issue. Also, is this perhaps a "mobile" Athlon processor? Is the PSU a quality unit? What model of mobo? No, regular athlon & Shuttle AN35 mobo Grativo |
#6
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What happens if you press the reset button on the computer when it
fails to boot with power being turned on? (Leave the power on for this test) I'll try this when I get home. If the pulse from the PS does not occur fast enough the MB logic will not reset and consequently not boot the computer. What is the solution to this problem? Grativo |
#7
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Grativo wrote: What happens if you press the reset button on the computer when it fails to boot with power being turned on? (Leave the power on for this test) I'll try this when I get home. If the pulse from the PS does not occur fast enough the MB logic will not reset and consequently not boot the computer. What is the solution to this problem? Grativo For most people, it would be to buy a replacement PS or live with the problem. I have not modified this circuit on ATX power supplies, but on AT power supplies you could trace the PG lead and look for an R/C circuit to modify after the comparitors. It was not unusual for the cap's value to change enough to cause a timing problem. This is NOT recommended for those with limited electronic knowledge. One other thing you might explore if you have this computer on a UPS, is plugging it (the PS) into wall and seeing if there is any improvement. My UPS is NOT a pass through type and a lower input to the PS if it was turned on at the same time "might" provide a similar result. This is only a theory, but it seems to occur with my UPS. If I defer turning on the computer until after the UPS has been on for a couple of seconds, I see this problem less on my computer. It could be coincidence, but it might cause the PS voltage to rise slower? |
#8
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For most people, it would be to buy a replacement PS or live with the
problem. I've tried pushing the reset button when it fails to boot and still no go. I really don't think it's a power supply problem because I've tried it on 3 different power supplies, and it still does this... Grativo |
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