computer hangs on a black screen

[zenyora]

hey all
as the title says my computer turns to a black screen and just hangs with a high pitch coming from speakers
the first time this is happened was during #The Last Remnant# around the same part every time which is not far into the tutorial game play.
2 days ago i bought Demigod and same things at some point during the game, the screen would turn black ,audio clip stuck.
at first i thought it might be that the cpu isnt getting enough power because i am only using a 4 pin , but that wasn't the case. i ran prime 95 on large fft, intel burn , 3d mark06, 3d mark vantage, memtest, chkdsk, and all passed just fine no errors no crashes nothing.
go back into demigod play for around 10 min and its a black screen of death. tried again lasted longer then again the same issue and a manual restart required.
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my specs :

Operating System Microsoft Windows Vista Ultimate

OS Service Pack Service Pack 1

Internet Explorer 7.0.6001.18000

DirectX DirectX 10.1

CPU QuadCore Intel Core 2 Quad Q9550, 2833 MHz (8.5 x 333)

Motherboard Gigabyte GA-EP45-UD3P
Motherboard Chipset Intel Eaglelake P45

Memory 4096 MB (DDR2-800 DDR2 SDRAM)
DIMM2: G Skill F2-6400CL5-2GBPQ 2 GB DDR2-800 DDR2 SDRAM (5-5-5-15 @ 400 MHz) (4-4-4-10 @ 266 MHz)
DIMM4: G Skill F2-6400CL5-2GBPQ 2 GB DDR2-800 DDR2 SDRAM (5-5-5-15 @ 400 MHz) (4-4-4-10 @ 266 MHz)

BIOS Type Award Modular (11/14/08)

GPU ATI Radeon HD 4850 (RV770)
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if any body knows what might be the problem please let me know.
Thanks

 

[KSoD]

Are the games up to date with the latest patches?

 

[zenyora]

both don't have any patches and i seem to be the only one having this issue

 

[KSoD]

Are you running Vista 32 bit or 64 Bit?

 

[zenyora]

hey sorry for the late reply ...
but i have vista 64 , and recently i bought another game(crysis warhead)and just few seconds into the game the screen turns to a black screen the white stripes and just hangs..at this point i know its not software but something wrong in hardware , but what is driving me crazy is none of the tests was able to crash my pc...i am at lost here ...any help guys

 

[KSoD]

Have you run MemTest86+?

 

[zenyora]

yep..you can see all the tests that i ran in my first post ....

 

[KSoD]

MemTest and MemTest86+ are not the same thing...

Have you installed SP2?

 

[zenyora]

well i finally found a test that resulted in the same problem ...FURMARK ..it reproduced the same problem just few seconds from running it stability test . does that mean the problem is the gpu?

 

[MrCoffee]

are you monitoring the GPU core temps whilst running furmark? check out something like GPUZ. When you say a black screen crash do you mean a spontaneous reboot? if so then it's probably a power issue so monitor the voltages/amps too, What PSU do you have? Or do you mean the computer just locks up with a black screen? that could be hardware or drivers, make sure you have the right drivers for everything (check event viewer for exceptions) flash your bios etc..
If you have any overclocks then set back to stock, even if only briefly just to rule that out as a problem.

With the high pitch coming from your speakers, are we talking a diagnostic alarm/beep type thing or just sound card gone nuts? Which is another thing, it may sound odd but don't rule out sound driver problems with gfx crashes, sound runs in directx too, try setting hardware acceleration for sound down to the minimum hardware setting (basic?) in dxdiag.