http://www.boards.ie/vbulletin/showthread.php?t=2056446392

Have an Intel Quad Core Q9550, running at 2.83GHz stock. Have oc'ed the CPU from 2.83GHz to about 3.2GHz. CPU temp is about 35 degrees, going up to 51 degrees when I run Prime95 on "Torture Test".

When I run BF3, it runs, it goes onto the "loading level" screen, and then just freezes the PC. If done in windowed mode, it goes into the level, and then it freezes. Quite annoying. It has only been happening since I overclocked it.

Overclocked settings:
CPU Clock Ratio: 0.5
CPU Host Frequency: I think it was about 410. ***
FSB +0.15V
(G)MCH +0.20V
Vmem +0.3V

I have a TRUE120 cooler stuck to the Q9550, if anyone is wondering.

I have since loaded default BIOS settings, but this continues to happen. I've ran Prime95 on "Torture Test" for 4 hours without any problems on all four cores.

Now, I'm thinking it may be graphical related, as it froze sometimes when I tried to update the HD4870 graphics card (after I set it to default settings again), and only seems to freeze when I run the game, not when loading the game. Based on advice from a few websites, I had changed the "PCI Express Frequency (Mhz)" from "auto" to 100mhz before overclocking anything, as I read that if left on auto it would increase in speed with in tune with the increase of the CPU. This has been put back to "auto".

So I'm wondering if it is in fact the graphics card on high load that is causing the crashes, what would be the best way to sort it out, if at all possible?

*** I think I accidentally did 100 at one stage  but the computer didn't accept this, and reset it to the default when I tried to save and reboot.

Ran FutureMarks 3dMark. PC froze the moment it started the graphics section, so that confirms that it's most likely the graphics card as Prime95 ran without any problems for CPU and RAM. The card is 3 years old so a replacement shouldn't be that costly. My only problem is that if I overclock the CPU when I get the replacement graphics card, I may damage the new card as well, which won't be an option

Would prefer to get this fixed. As it works unless I put a massive load on it, it can't be totally fubared, can it?

/edit
Forgot to mention: after 30 or 40 minutes of it freezing, the computer restarted itself.

Any ideas or comments would be nice.

Dont overclock shit, it will only shorten the life of the component in one way or another.

I'm trying to figure out why the graphics card went when I didn't overclock it. As for overclocking, meh; the machine is 3 years old, so may as well see if I can push it a little. May as well figure out what went wrong with this machine before I go onto a new machine. May get a cheap ?50 card (eg: MSI Radeon R5450) to tide me over until after Chrimbo when I do a full update of the system.

Yahooo... fixed it; BF3 works again

What I did: took the 4870 out, cleaned the dust, took it apart, cleaned the thermal paste off it, put new thermal paste on, put a bigger fan on it, put it back in, booted machine, played some BF3. Pictures etc of what I did will follow tomorrow

You didnt fix it really!  It was him wasnt it.....

Meccano!  Played sir.  I look forward to your LEGO mod...