Windows 7: HDMI 1080p Shuts off computer (please help)

AT first i thought my Graphics card was failing so i unplugged it and hook to the vga on my onboard graphics of my 8200 MOBO XFX.... No problems for Hours... So I hook it to my 52inch Sharp Aquos using a dvi-hdmi adapter.... Run it at 720 for hours.... No problem.. So im like damn my graphics is going... But then i put the settings to 1080p and 10 minutes later it shuts down as if it were overheating... But its barely capping at 65celcius So thats not it... I hook my 9800GT OC-SC run it at 720P at minimum clock settings no problems for hours running 80-120fps on my game... So i switch to 1080p still running around 70-90 fps and the GPU is at 63celcius... 10 minutes later it shuts down like i just pulled the cord or like its overheating... (Which it is not)

Specs:
500watt Ultra PSU
Cooler Liquid Cooled 1-3 coolant solution...
5 120mm Fans X-Dream Case (flows amazingly)
3 80mm Fans for exhuast 2 Rear one front
XFX 8200 2.88ghz-x4 Proc 1gb Ram
9800GT Superclocked 512ddr3

Its not hardware for sure at this point so has anyone found fixes to this or am i pretty much stuck at 720 on massive tv's?

Also It doesnt shut off if I take off the side panel and run 1080p with a Massive fan... Wierd huh? VGA Runs fine at 1920-1050 any help would be greatly appreciated...

Also to add i have a GTS 250 Overclocked 1gb ddr3 on its way because i was impatient and thought my graphics card went... any how im upgrading to this soon but i want to know why it would be doing this... Im hoping to run 1080p on this nice new up to date card... So any help would be greatly appreciated!

Don't know for sure - but what kind of HDMI cable are you using?
What kind of DVI adapter? DVI-I? DVI-D?

The reason I ask is:
A few years ago, HDCP was introduced. It's a hardware-level copy protection method.
This prohibits devices from operating at 1080p if both the source and the viewer are not HDCP compliant. Even the cable connecting the devices has to be HDCP-capable.


I do not know for sure if this is problem - but I would place my bets on either your HDMI cable or DVI-HDMI converter causing the issue.

Are you sure your TV can handle the resolution?

Apparently there are different screens in the same-name models and only the latest versions can run @ 1920x1080

You will kill your screen/TV by forcing it to run at a higher resolution than it can handle!

If you are using an adaptor then you aren't getting true HDMI and there is no way to get 1080P using an adaptor from DVI. Try for 1080i instead.

What exactly do you mean?
DVI signal is HDMI without sound as I understand.

I just double checked my 7.1 Yamaha AV receiver (on screen display) - says it is receiving /passing thru a 1080p signal.

That's with a DVi-HDMI adapter,
HDMI lead + Digi_Optical spdiff lead from 'puta
Hdmi lead out to monitor/HDTV from AV receiver OUT.