Black screen....changed gpu, psu, monitor...mobo dead?

Hey all, I bought a Mesh Elite Quad 6600 FX in sept '07...

system spec
Q6600 at stock 2.4ghz, asus 650i sli (P5N-E SLI), 8800GTS 320mb, seagate barracuda 250gb oem (boot disc), 4x1 ddr2 667mhz samsung ram, HEC 550W, GNR 19" widescreen monitor, 32 bit vista,

Haven't made any overclock or anything from from system bought sept '07; only internal change was added 2nd hard-drive..Western Digital 1TB caviar black (WD1001FALS) from dabs, installed in jan-feb 2009; computer was working fine until about 3-4 weeks ago....

....PC was starting to get black screen as if on standby. if restarted a few times or left for 20-30mins, screen would come back up (to the enter password screen etc)....once on, was ok and could leave on 24 hrs+ no problems.....could also play games like mass effect etc but took a fair bit longer than normal when initially opening the game (a minute or so) and alt-tabbing back between windows and game (about 8-12 secs). was stable once in game though, no excessive lag/solid framerates.
Couldn't always leave my PC on though obviously, so would switch it off and after a few days problem got worse; could take an hour of restarts, switching monitor on and off, holding monitor on button etc...still would come back up after a while....

...but then Switched off after going away for the weekend (21st june)....came back, and screen signals have never come back on again since, don't even see bios, just pure black screen all the time, and monitor stopped showing any light (standby etc), just black screen. However could hear booting into windows, it recognised login password, could hear windows intro theme to validate that it got to desktop. Power down worked properly, controlled shutdown/takes the time to close apps etc.
As no monitor standby light anymore, thought most likely culprit was that monitor had died, bought a new samsung 19” widescreen TFT (rose).....same problem of black screen with new monitor....if switch on, get a samsung logo come up, top left corner scan for analogue or digital (about 7 turns alternating, before ending on digital), then solid red on light goes to flashing standby red....but no signal from the comp...just black...

So cracked open the case; fans are working, motherboard LED working, cleared dust with compressed air (was reasonably dusty admittedly), reseated gpu, checked power connections, changed cmos battery, reset cmos jumper (left for about 10 minutes), tried booting with dvd drive and fals 1TB caviar black unplugged from psu and mobo, tried core system with just 1 individual ram stick on it’s own (tried each) and boot drive (250GB). Tried holding power button for 1-2minutes with 3-pin AC unplugged. Tried getting into safe mode, when switched off it powered down immediately after so I guess it booted into that. Still no screen trying safe mode. tried old school mouse and keyboard instead of wireless usb.

as all that made no difference, and as assumed mobo/cpu wouldn't boot into windows if error was on those two...I thought it was probably faulty gpu then, or possibly psu had degraded (train of thought was longer times starting up games/alt-tabbing was the psu taking longer to power up the gpu), replaced psu/gpu with corsair TX850W and XFX GTX 260 black edition.....put those into the system, but still black screen, tried two other gpus who a friend brought back from his work, still no difference.
Tried disconnecting seagate barracuda 250Gb which is still the original boot disc, and leaving caviar black plugged in instead hoping it would go into bios or something, still no difference.

So...I think I’ve isolated it’s not dvd drive, not either of the hard drives, not gpu, not psu, not cmos battery, not monitor...not ram I don't think (can you test 1 stick in the other slots, I just tested in furthest left (slot 1)).
regards software/3rd party, Would've thought I'd be able to get into safe mode if nvidia drivers (which I haven't updated for ages as current ones were doing alright), or third-party software eg. if an unknown virus had changed anything....same thoughts if somehow refresh rate or resolution had somehow changed to an unsupported one....would've thought safe mode would work or that it would've been a more immediate error, as opposed to this where it slowly seemed to degrade (ie. struggling to come on, but once was on it worked, until finally dying).

haven't heard any mobo beeps so far, other than a high pitch squeel from the 8800GTS when I accidentally didn't plug it in after reseating it once (piezo-electric siren).

so dead mobo across the PCI-E?...or CPU? Any ideas? :confused:

3 answers Last reply
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  1. I don't see any mention of you trying a different video cable, did you try that? They do go, and I have had more than one defective cable directly from the factory with Samsung monitors.
  2. sorry, yeah. was new dvi cable that I used with the new monitor. still no difference.
  3. See if you have a loose part in your case shorting out the motherboard, if you don't fine anything that every thing out of the case and hook it up outside of the case, see if it works. If it doesn't you probably need a motherboard.
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