Older (Core 2) computer hangs or power cycles

[isandu]

Config: Core 2 Quad Q6600 (previously @3.1GHz, now stock @2.4GHz), 4GB DDR2 Mushkin 800MHz CL4 (2 x 2GB), Gigabyte P35-DS4 (dead on-board NIC & onboard sound), 100Mbit Realtek PCI NIC, HIS Radeon HD 4850 512MB stock, Windows 7 64-bit, Thermaltake 450W PSU, 1TB Samsung Spinpoint F3, 640GB WD AAKS, 250GB Seagate 7200.10, Razer BlackWidow USB KB, Mionix Naos 5000 USB mouse, DVDRW.

Short story: computer boots but freezes not long after booting (both in Windows and in BIOS - USB keyboard and mouse always turn off when it freezes), or continuously power cycles without posting, especially after a reset. I tried a different PSU, disconnecting the 250GB HDD & DVDRW (the other two HDDs are needed for booting), but the same problems occur.

Details:
A few days ago, I found the monitor turned off, the USB mouse & keyboard leds turned off, the computer frozen, with the power and hdd leds on. After a reset I tried to boot the computer, but it would turn on and then immediately turn off again, over and over (no post). I assumed the PCI network card died again, perhaps from a surge caused by lightning (we've been getting heavy raining lately, and this happened before two years ago, the computer wouldn't boot at all until I took the dead NIC out). Next day, I took the NIC out, this time the computer booted into windows, but evetually it would always freeze at some point, idle or not - the keyboard and mouse leds (both USB) always turn off when it does this. I tried to run Batman Arkham Asylum, the computer froze immediately. The computer freezes even in BIOS - with the same symptoms. Sometimes it doesn't even post, it cycles over and over like the first time (but it seems to do this after I reset the computer when it freezes, it doesn't seem to do this after it's been off for a while). I tried putting the NIC back in again, the computer sometimes boots but the same problems occur (maybe it wasn't the NIC that caused this after all).

Another weird thing: when off the computer used to consume ~13W if the PSU switch is on, now it always consumes ~20-21W with the same PSU. So, I suspected the PSU, but I tried a different PSU (very crappy but I used it before to boot the same config) and the same thing happens. So I think I eliminated the PSU as being the culprit, or at least the only culprit.

One colleague suggested taking out a RAM stick at a time, I'll try this when I get home. I suspect the MB or video card (though they both use solid capacitors & all computer fans work OK). I don't have a spare video card to test right now, but I hope I can manage to find one next weekend.

Any advice is welcomed.

 

[Puppies04]

Have you pulled the CMOS and reset the board? Just an idea before you start tinkering.

 

[isandu]

Have you pulled the CMOS and reset the board? Just an idea before you start tinkering.

No, I haven't tried that yet. I'll try it when I get home. Thanks for the advice.

 

[sm625]

If standby is pulling 20 watts then it needs to go in the trash.

 

[dbailey]

I had a motherboard that had the usb ports fried. It resulted in the same type of behavior.

If you already tried another psu, run memtest on the ram, do a new OS install, and then you'll have to replace the mobo if none of the above work.

 

[isandu]

If standby is pulling 20 watts then it needs to go in the trash.

Yes, even 13W seem a little bit too high while the computer is turned off. Now, even the the PSU power switch is turned off completely, it still pulls 0.9W.

But unfortunately, it will probably take a few months to save the money for the new build I've been dreaming. I've been hoping the current build would last me until Haswell.

 

[isandu]

I had a motherboard that had the usb ports fried. It resulted in the same type of behavior.

If you already tried another psu, run memtest on the ram, do a new OS install, and then you'll have to replace the mobo if none of the above work.

I have a Memtest CD somewhere, I'll try that too. But the computer freezes even in BIOS, I don't think it can last much in Memtest, let alone through a new OS install.

 

[Ketchup]

I have a Memtest CD somewhere, I'll try that too. But the computer freezes even in BIOS, I don't think it can last much in Memtest, let alone through a new OS install.

You are correct, these can be tricky since there is little to be done aside from swapping parts. I fear it is the motherboard. Maybe you can find a nice eBay deal to hold you over.

 

[sm625]

With it pulling 20 watts in standby, you may be able to find a part that is getting warm. Maybe your sound chip or your LAN chip. After it has been running for a while, try feeling all the little chips. If you find one that is getting hot you may be able to desolder it or even cut it out of the board and have the board still work just fine. This is obviously a last ditch effort. I wouldnt go cutting out VRMs and definitely dont cut out your bios or one of the bridge chips! But your mobo should work just fine with a gutted sound or LAN chip.

 

[isandu]

Sorry I couldn't reply sooner but the computer at home is the only Internet connected device I have, and it's still not working. I did a CMOS reset and loaded all default settings, pulled out a memory stick at a time, tried booting in Windows XP, disconnected all USB devices (used an old PS2 keyboard and mouse), but the computer always freezes after a brief while. I haven't tried Memtest because I felt it would have been useless at this point.

You are correct, these can be tricky since there is little to be done aside from swapping parts. I fear it is the motherboard. Maybe you can find a nice eBay deal to hold you over.

With it pulling 20 watts in standby, you may be able to find a part that is getting warm. Maybe your sound chip or your LAN chip. After it has been running for a while, try feeling all the little chips. If you find one that is getting hot you may be able to desolder it or even cut it out of the board and have the board still work just fine. This is obviously a last ditch effort. I wouldnt go cutting out VRMs and definitely dont cut out your bios or one of the bridge chips! But your mobo should work just fine with a gutted sound or LAN chip.

If it's just the MB that's defective, it's not that bad to replace it. The only new LGA 775 motherboards I can still find where I live are G41 mATX 2-slot DDR3 boards, but at least they are cheap, and with two slots of DDR3 I can still get 8GB of RAM (and for the same amount of money I would pay for another 4GB of DDR2). There are also used boards for sale, I'll explore those options too.

Thank you for your advice guys.

UPDATE: I replaced the MB and now everything works OK. Power consumption when off is now 3W. It's obvious now that there was something wrong with my old motherboard.

Thank you for your help.