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#21
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Nick G wrote:
It was tested in two different properties in different parts of London and on multiple mains sockets. I am writing this in one of those properties and on a working laptop which is being mains powered with no problems. The most bizarre thing about this problem is that i have replaced every single major component at least once if not twice and have still got the problem! Including mobo? I still think you need to study the capacitors, maybe test them. -- ~misfit~ |
#22
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I agree...get a "reputable" PSU to troubleshoot with. All symptoms point
most likely to a PSU not up to snuff. I recommend an Antec, Enermax or Sea at 400W or higher, and plug it into a UPS as well. Russell http://tastycomputers.com "Mantric" wrote in message ... Can I just chip in here and suggest a different PSU as maplin know jack sh%# about anything to do with computers. I have a variety of PSU units here that caused problems similar to yours and two of them are newish Q Tec 400 watters. You can get a resonable 400 watt unit made by Nexus from Novatec for 55 quid. -- Mantric |
#23
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Nick G wrote:
thanks. caps on both boards look fine. no leaks or discolouration. No bulging either? Top or sides? Sometimes capacitors from three years to about 18 months ago can fail but still look ok. Usually they'll bulge though, not always. I've had this problem more than once. It only takes one cap to cause problems. -- ~misfit~ "BigStan" wrote in message ... He means bad capacitors. Sometimes they go south and cause instability. Link here - http://www.motherboardrepair.com/ "Nick G" ignore @ nospam.com wrote in message ... Bad Caps. Can you expand on this? thks n |
#24
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Sorry, meant to say:
"I recommend an Antec, Enermax or Seasonic at 400W or higher" |
#25
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My wild guess, which it is, is that you have a single component on the
motherboard (capacitor, chip, etc), which you haven't tried switching out apparently, with a thermal fault that occurs over time during operation. I think your next step is to replace the board. -- DaveW "Nick G" ignore @ nospam.com wrote in message ... The following problem has confounded every IT friend and support person i have presented it to and appears to defy logic so i am throwing it to a broader audience of experts to see if it elicits some ideas. Thanks in advance for considering it and apologies for cross-group posting! Problem: Spontaneous power-offs that take place between 15 seconds and 30 minutes after booting. As if the power cord was yanked out of the back. Green M/B LED remains on, power cord has to be disconnected for several seconds before re-boot can take place. PC background: home-built 18 months ago, ran fine until last week. I have been building PCs for 15 years and have spent the last week running through every permutation of test i can think of, to no avail. Components tested (all of which have, in every configuration, replicated the problem): M/B Asus a7v333 latest bios Asus a7v8x-x v06 bios - rejects flash to latest 08 bios temp problem? No. M/B temp under 35 degrees c at time of power-down (have been staring at PC probe's temp montitor as it has gone down on 2 occasions. Immediate boot-ups after power-down reveal no discrepancies in bios-based temp monitor i.e. also reports 35 degrees c or under) CPU AMD Athlon 2100+ AMD Athlon 2500+ temp problem? No CPU temp under 40 degrees c at time of power-down (have been staring at PC probe's temp montitor as it has gone down on 2 occasions. Immediate boot-ups after power-down reveal no discrepancies in bios-based temp monitor i.e. also reports 40 degrees c or under). Bios-based auto-shutdown set at 95 degrees c HD 8GB Seagate- freshly fdisked/formatted but fails to complete winXp install (lasts between 15mins and 25 mins) before powering off 20GB IBM- Win98SE - exhibits power-down symptoms every time, works fine on other machines. Lasts the longest time, up to 30 mins, running in 640x480 res 80GB Maxtor - Win Xp Home - lasts the shortest time, rarely more than 15 minutes, power-offs can happen without any apps running but tends to happen within a few seconds of 3Dmark03 running and within 15 minutes of Norton AV2K4 running Software problem? No. problem replicated with winxp install on fresh disk. Also run each HD in isolation to others, i.e. with no other no HD IDE/power connections Graphics Radeon 9800pro - exhibits power-down symptoms every time, works fine on other machines Radeon 9700 Pro exhibits power-down symptoms every time, works fine on other machines GeForce Ti4600 - exhibits power-down symptoms every time, works fine on other machines Graphics card problem? maybe, but three different cards have replicated the problem. Run with default VGA drivers and latest drivers Memory 512Mb PC2700 Apacer CL2.5 512MB PC3200 Infineon CL 2.5 Memory problem? maybe, replicated with both DIMMS though. Could it be a voltage issue? everything set to default in bios and no voltage setting tampered with at any stage. PSU 300W unbranded, came with case 400W high quality, multi-fan Power problem? Dont know. the brand new 400w PSU immediately replicated the problem. Have tried 4 different power cords in two houses on 5 different sockets (!). All replicated the problem. Others: case - generic, have tried running the pc out of the case without any case jumper connections or any other connections other than PSU housing, using screwdriver to boot. CD, DVD, Floppy, Soundcard, USB expansion card, game card expansion, other USB connections - taken out/disonnected (ide, power etc) but problem still exists I have even tried, once an app is running, diconnecting mouse, keyboard and monitor (!!) with the problem still taking place. I have effectively changed PC entirely with these tests and still get this problem! One idea that was thrown out was a bios-residing virus. is there such a thing (i cannot find mention of one anywhere let alone scanning or removal methods)? Does anyone have any other ideas? Any help very much appreciated Nick ps Please post reply (e-mail address is false) |
#26
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On Wed, 11 Feb 2004 12:43:21 +1300, "~misfit~"
wrote: Nick G wrote: It was tested in two different properties in different parts of London and on multiple mains sockets. I am writing this in one of those properties and on a working laptop which is being mains powered with no problems. The most bizarre thing about this problem is that i have replaced every single major component at least once if not twice and have still got the problem! Including mobo? I still think you need to study the capacitors, maybe test them. .... but he's tried two different motherboards |
#27
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i am currently using the brand new a7v8x and can see no bulging...
"~misfit~" wrote in message news Nick G wrote: thanks. caps on both boards look fine. no leaks or discolouration. No bulging either? Top or sides? Sometimes capacitors from three years to about 18 months ago can fail but still look ok. Usually they'll bulge though, not always. I've had this problem more than once. It only takes one cap to cause problems. -- ~misfit~ "BigStan" wrote in message ... He means bad capacitors. Sometimes they go south and cause instability. Link here - http://www.motherboardrepair.com/ "Nick G" ignore @ nospam.com wrote in message ... Bad Caps. Can you expand on this? thks n |
#28
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kony wrote:
On Wed, 11 Feb 2004 12:43:21 +1300, "~misfit~" wrote: Nick G wrote: It was tested in two different properties in different parts of London and on multiple mains sockets. I am writing this in one of those properties and on a working laptop which is being mains powered with no problems. The most bizarre thing about this problem is that i have replaced every single major component at least once if not twice and have still got the problem! Including mobo? I still think you need to study the capacitors, maybe test them. ... but he's tried two different motherboards G Yeah, I missed that bit in this extensive thread. That's why I asked "Including mobo?" -- ~misfit~ |
#29
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Nick G wrote:
i am currently using the brand new a7v8x and can see no bulging... Yeah. Sorry Nick, I missed that bit. G I guess I should read fewer newsgroups and read the ones I continue with more thouroughly. Good luck with your interesting problem. A great opportunity to learn. -- ~misfit~ "~misfit~" wrote in message news Nick G wrote: thanks. caps on both boards look fine. no leaks or discolouration. No bulging either? Top or sides? Sometimes capacitors from three years to about 18 months ago can fail but still look ok. Usually they'll bulge though, not always. I've had this problem more than once. It only takes one cap to cause problems. -- ~misfit~ "BigStan" wrote in message ... He means bad capacitors. Sometimes they go south and cause instability. Link here - http://www.motherboardrepair.com/ "Nick G" ignore @ nospam.com wrote in message ... Bad Caps. Can you expand on this? thks n |
#30
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"Nick G" ignore @ nospam.com wrote in message ...
The following problem has confounded every IT friend and support person i have presented it to and appears to defy logic Spontaneous power-offs that take place between 15 seconds and 30 minutes after booting. home-built 18 months ago, ran fine until last week. I have been building PCs for 15 years Asus a7v333 latest bios Asus a7v8x-x v06 bios - rejects flash to latest 08 bios Radeon 9800pro - exhibits power-down symptoms every time Radeon 9700 Pro exhibits power-down symptoms every time, GeForce Ti4600 - exhibits power-down symptoms every time, 300W unbranded, came with case 400W high quality, multi-fan the 400w PSU is made by Q-Tec and What did you learn in your 15 years of building PCs? You should have measured voltages, lightened the load (not by swapping one power hog of a video card for another), and tried a high quality power supply. Those motherboards rely on +3.3V and +5V almost exclusively, and combined with a high-power video card, many power supplies just can't handle the load. It's possible that your 300W was marginal but weakened as its capacitors aged, and the Q-tec may have been inadequate all along. Anyone with 15 years of experience building PCs should have noticed instantly that the Q-tec was crap by simply peeking through the vent holes and seeing all the empty space and small heatsinks and transformer. Borrow, buy, or steal a good supply, like an Antec (AKA Channel Well, but only if its +3.3V is rated for at least 20A and its +12V for at least 15A), Fortron (many names, like Sparkle, Aopen), or something used by a major computer manufacturer, except Dell (wires mixed up, will destroy motherboard when plugged in). |
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