I've recently upgraded my old Athlon 64 X2 based system with the following components:

Core 2 Quad Q6600 G0
Gigabyte G33M-DS2R motherboard
4x2GB Corsair XMS2 RAM

I've had the system up and running for about a week, running overclocked to 3GHz. It passed Orthos and Memtest fine at these speeds. In the last few days, my machine has kept on occasionally locking up. When I looked at my system temperatures, everthing seemed fine except for the graphics card which seemed to be massively overheating. Thinking this was the problem I've removed the card and gone to onboard graphics, but I'm still getting the lockups. The same problem occurs at the stock 2.4GHz and I've even underclocked to 1.2GHz (6x200) and still the lockups happen. The only disturbing thing I can find is that the processors VID is 1.325 but CPUZ is reporting it as being way below that. I have a decent power supply (Seasonic S12-II 500W) so I don't think this is the problem. I've also tried running a prime burn in test off a bootable CD in case the windows install has somehow become corrupted - the system hung after about 5 minutes. I also occasionally get lockups in the BIOS after immediately resetting the PC when this happens.

I've attached a CPUZ / Coretemp screenshot in case it helps. I'm completely at a loss as to what the problem is, so any advice would be greatly appreciated.

Unfortunately that could be anything. I would recommend putting things to stock and trying to eliminate other causes first. Most new MoBos share interrupts now a days, and I had a network card that didnt comply with its orders. It was on a channel with my 8800Ultra, and normally this is fine.

BUT... on my system, at random times when the wireless card would send out its search for wireless network pulses it would just lock my system up. It was random, but would always do it pretty fast. I had to just manually assign it a different Irq and now poof, no sudden freezes. Boy, was fun tracking it down!

But I thought it was some OCing settings. Funny thing... OC settings usually cause weird things yer not supposed to see in Vista to fail. Superfetch, windows desktop manager, windows explorer. Or more times than not, the BSOD! Oh yes, The Infamous Blue Screen MUST save your computer from impending doom!
Dont just terminate the offending program, nope, total blue screen.

Anyways, just disable the onboard thingies one at a time in the bios, starting with a mass disable of what you dont use anyways. I have two onboard lans disabled, the 1344, the E sata junk... then move on to things you use. Who knows, could be a simple irq problem and you're free to OC to Umbutuland! (Someplace like that!)

--Lupi!

Thanks for the reply. I've been fiddling round this afternoon and I think I've found the problem. I believe the northbridge is overheating - with my case fans on minimum the machine will lock up at stock clocks within about 10 mins. I think the reason it was locking up at lower frequencies was that the NB didn't have time to cool down in between runs. I guess having a graphics card running at 110C next to the NB dosn't help either.

I've managed to get the machine running stable at stock speeds if I whack my case fans onto maximum, although I'm not comfortable leaving them at this setting as I like to have spare cooling capacity for the summer months. I've reduced the FSB and MCH voltages by 0.15V in the BIOS (the max it will let me undervolt by) to try and reduce the heat output. I guess the only other things I can do are get another case fan pointed directly at the NB and hope that the reduced heat output from my next graphics card will help.

110 c? You do know that prolly isnt good. Your chipset shouldnt overheat on its own, by the way, hehe. I'd be more worried about that vid card! Are you able to monitor the temps of your NB? Try HWMonitor if you cant normally see it in windows.
But.. if the voltage is back to stock and all that. You should not have a heat problem. Can you tell if the sink on the NB looks moved or missplaced or damaged? Is it firmly attached?

--Lupi

Yeah, I've just ordered a 3870 to replace the graphics card

My theory about the northbridge overheating has just been blown out of the window. It's locked up again this morning on all stock settings within 15 mins of turning it on. Immediately after the lockup I felt the NB heatsink and its far cooler than it was yesterday. It seems firmly attached although it is being slighly covered on top by a few millimeters by my artic cooling heatsink on the CPU. All I was doing was running a defragging program and running a web music player and web browser - nothing that's putting a huge load on the system.

I'll try disabling things in the BIOS as you suggest and I'll also look at that program. I'm already running a fairly minimal system as I always disable things I dont use, but theres probably one or two things I can turn off. The system hangs without any add in cards in the system.

I tried disabling all non essential options in the BIOS, still getting the problem

I've downloaded that tool as you suggested. Seems pretty comprehensive! Here's what I got out of it:



There are two things that seem a bit off in that. The CPU voltage seems very low (its VID is 1.325), although I raised the voltage manually to 1.4 in the BIOS which gave about 1.34 in HWMonitor, but the lockups still happened. The other thing I found curious was the RAM voltage - this is being reported as 1.95 however I think that the RAM i have is supposed to run at 1.8:

http://www.corsair.com/_datasheets [...] 6400C5.pdf

There isn't any option to manually alter the RAM voltage downwards in the BIOS - I can only overvolt it by +0.1 to +0.4V

The reason why the voltage in the bios, or the VID, is higher than what other programs are reading is due to Vdrop and Vdroop. VID is the highest the cpu voltage will ever go, and if the voltage does go beyond that, you system will crash and have issues.

First, take out all but one ram stick and see if the pc runs. If it fails, switch slot using different ram sticks. Play around with the ram settings, using lax timings such as 5-5-5-15 and low voltage like 1.9v (+.1).