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#21
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Buy replacement parts that will accomodate future upgrades, so there
isn't any significant money wasted, you'll be on your way towards a faster system still. Agreed - unfortunately, the power supply does not appear to be the problem. I took one out from a working machine and I still get the same problem. This is symptomatic therefore that the problem is either mobo or cpu related or even a combination of both, I can therefore conclude? If so, I'm going to have to buy a new base computer, because this is very expensive territory now. Co-incidentally, if I want to test the CPU works in another machine can I just swap a 1Ghz AMD Athlon for a 1.3Ghz AMD Athlon? And if the CPU is in fact damaged, could it cause damage to the undamaged machine? Or vice versa - if the motherboard is fried, could placing a good CPU in it damage the good CPU? |
#22
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The POST won't run until after the reset (to make sure all devices are
ready to be polled). If you don't see the flash of the keyboard LEDs then there was no reset signal to prep it or anything else. The reset signal to the CPU is held low until the PSU voltages stabilize and then the CPU sends a reset pulse to all devices. If you don't see the lights flash on the keyboard, it could be because the CPU never sends the reset pulse (which indicates it is defective) or there is a problem with the motherboard, like it got damaged by a surge or from improper handling (i.e., no anti-static protection). I did assume that the "normal" keyboard you tested with is NOT a USB keyboard but instead connects to the PS/2 or AT keyboard port. I don't know how USB keyboards respond to a reset signal since it would be the USB controller that got the reset and not really the USB keyboard. Note that testing a power supply just to check its voltages is not a sufficient test. Something that tests at +12 volts with no load might end up being much less under load. There are PSU testers that you can get, like at CompUSA, Antec, or FMI, that put a *slight* load on the PSU to check its voltages. Or leave the PSU connected to the motherboard and all devices and shove the probe tip into the backside of the 4-pin Molex power connector to measure voltages under load. it also possible that regulation sucks and there is so much ripple as to not actually provide the average power and voltage that is needed, but you can only see that with an oscilloscope. I never asked but didn't think of it since normally a user would've already mentioned this. When you power up the system, do the hard drives actually spin up? That is, do you actually get power when you think you have powered up? The ATX power supply will not actually power up (except for a 5V line) until the PS-On signal on the motherboard's 20-pin header to which the ATX connector attaches is no longer pulled low. If the motherboard isn't releasing the PS-ON line (pin 14) then the ATX power supply will not turn on the rest of its power taps and nothing gets powered up (so neither would the hard drives which you can do not spin up). See http://snurl.com/2mt4 where I answered a question about PS-ON. -- __________________________________________________ __________ *** Post replies to newsgroup. E-mail is not accepted. *** __________________________________________________ __________ "ck26" wrote in message ... If you have no video at all, a defective video card whose BIOS won't load will kill the POST right away. Yank out the video card and you should get, I think, 1 long beep and 2 short beeps (for Award BIOS). Right - I have an onboard graphics card (which I can't remove) and a PCI card that was the card in use at the time of the "incident". I removed the PCI video card and nothing - still the same - no beeps. I can't really disable the onboard one other than by telling the bios to use the PCI rather than onboard AGP video - which I did when I first installed the new card. Either way, I'm pretty sure its not the video now. Do you see the LEDs flash on the keyboard? That's due to the reset signal. I connected a normal keyboard to see any lights being displayed upon boot. Nope. No lights. No beeps. See http://www.pcguide.com/ref/mbsys/bios/boot.htm for the boot sequence. Great stuff on the beeps - shame there's nothing about no beeps! |
#23
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the CPU sends a reset pulse to all devices. If you don't see the lights
flash on the keyboard, it could be because the CPU never sends the reset pulse (which indicates it is defective) Hmm, possibly - could I do a straight swap with an AMD Duron 1.3Ghz? (its currently an AMD Athlon 1.3Ghz) - they are suprisingly cheap at my local store and worth a try. or there is a problem with the motherboard, like it got damaged by a surge or from improper handling (i.e., no anti-static protection). Nothing has been handled internally until after it happened. I did assume that the "normal" keyboard you tested with is NOT a USB keyboard but instead connects to the PS/2 or AT keyboard port. I don't know how USB keyboards respond to a reset signal since it would be the USB controller that got the reset and not really the USB keyboard. Yes it was a straight no frills PS/2 keyboard. Note that testing a power supply just to check its voltages is not a sufficient test. Something that tests at +12 volts with no load might end up being much less under load. There are PSU testers that you can get, like at CompUSA, Antec, or FMI, that put a *slight* load on the PSU to check its voltages. Or leave the PSU connected to the motherboard and all devices and shove the probe tip into the backside of the 4-pin Molex power connector to measure voltages under load. it also possible that regulation sucks and there is so much ripple as to not actually provide the average power and voltage that is needed, but you can only see that with an oscilloscope. I switched power supply with a working machine's - no difference unfortunately... I never asked but didn't think of it since normally a user would've already mentioned this. When you power up the system, do the hard drives actually spin up? Yes, I'm pretty sure - my fans are quite noisy, but I'm sure I heard it spinning. The HD light comes on anyway. That is, do you actually get power when you think you have powered up? The ATX power supply will not actually power up (except for a 5V line) until the PS-On signal on the motherboard's 20-pin header to which the ATX connector attaches is no longer pulled low. If the motherboard isn't releasing the PS-ON line (pin 14) then the ATX power supply will not turn on the rest of its power taps and nothing gets powered up (so neither would the hard drives which you can do not spin up). See http://snurl.com/2mt4 where I answered a question about PS-ON. Fair enough - a little out of my depth, but you sound like you know what you are talking about! |
#24
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The quickest and surest way to tell would be to look at the manual or
the maker's web site for that motherboard to be sure they say they support whatever CPU you were going to try. Unless I missed it, you didn't mention your motherboard brand and model. I don't really need to know since I'm sure you can browse to their site and hunt around as well as I. I mostly build my systems using Intels. Cost more but I prefer more robust components in addition or in lieu of external protection as is required for the AMDs. If the heatsink falls off an AMD, it can burn up and be destroyed in a couple seconds. It will survive a bit longer if just the fan stops spinning but it will eventually burn up. Newer motherboards provide protection against overheating but they don't seem quick enough to prevent thermally stressing the CPU and severely reducing its longevity and reliability. Older motherboards don't have this external protection. See Tom's review at http://snurl.com/amd_fried (note the smoke in a couple seconds, and in one case the system crashes before the tester can completely remove the heatsink). The Intels reduce their duty cycle to reduce heat so it doesn't get to a catastrophic level. The AMDs burn up without something to try to protect them. I consider the external protection against catastrophic overheating more to protect the motherboard from frying than to protect the AMD processor. The Tyan Trinity KT400 and Asus A7V8X handle Athlon XP, Athlon, and Duron. They don't mention any special instructions when using a Duron versus an Athlon. I would think that if it takes an Athlon then it will take a Duron. They both fit in a Socket A. You didn't mention which motherboard you have, but then you can visit the maker's web page as well as I. |
#25
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On Sat, 11 Oct 2003 01:08:51 +0100, "ck26"
wrote: Buy replacement parts that will accomodate future upgrades, so there isn't any significant money wasted, you'll be on your way towards a faster system still. Agreed - unfortunately, the power supply does not appear to be the problem. I took one out from a working machine and I still get the same problem. A machine of similar power usage, so the odds weigh in favor of it being adequate for this sytem? In other words, a PSU of adequate wattage and known quality? This is symptomatic therefore that the problem is either mobo or cpu related or even a combination of both, I can therefore conclude? If you feel confident you've ruled everything else out... If so, I'm going to have to buy a new base computer, because this is very expensive territory now. Surely you can find some way test your parts free or inexpensively? A lot of people do end up scrapping the whole system and starting over with a new one... I have stacks of OEM boxes in my basement as a result. Co-incidentally, if I want to test the CPU works in another machine can I just swap a 1Ghz AMD Athlon for a 1.3Ghz AMD Athlon? And if the CPU is in fact damaged, could it cause damage to the undamaged machine? Or vice versa - if the motherboard is fried, could placing a good CPU in it damage the good CPU? Usually not, but I've heard of it happening. Your present motherboard can't run a modern AMD CPU, right? You might buy the motherboard, memory, and try the CPU... the odds are it won't damage the board, and if it doesn't work you need a new CPU.... might be considered an acceptable, reasonable risk. Dave |
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