Core i5-2500K Overclocking issue....

connchri

Daemon Poster
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Scotland, UK
Right lads, long time no speak! Looks like a lot has changed around here.... Anyway, I could do with a wee helping hand..

After sticking with old faithfull for a couple of years too long, I finally went on a mad building spree and built a nice new rig. As usual, it was always destined to be overclocked. So, Specs are:

Core i5-2500K
4GB Corsair 2GHz XMS3 DDR3 (8 GB of the same stuff in the post and due to replace it)
2GB Asus AMD HD6950 (Unlocked additional stream processors and overclocked to HD6970 :D)
Asus P8P67-LE (Nice decent P67 Mobo with EFI and a few other bells and whistles - but none of the stuff I wouldn't use)
The rest is just your usual, 1TB HDD, Blu-Ray Drive, solid Antec 650W, etc etc...

Running a legit copy of Windows 7 64bit. All the drivers and updates installed, and running as sweet as a nut.

The CPU is overclocked from 3.33GHz to 4.532GHz (44 x 103Mhz - the FSB/Base clock of sandy bridge is sensitive to overclocks :( ). Nice little overclock there, and is kept rather cool with a Arctic Freezer Cooler Pro Rev.2. Tested for over an hour with Prime 95 and been used solidly for 2 days and temps don't go above 65 on full load, and is as solid as a rock.

So here's the problem, when running Prime 95 and using CPU-Z for monitoring the clock speed, the CPU duly sits at ~4.5GHz... for about 2-3 minutes, then it starts jumping from 3.3GHz to 4.5GHz. I've Intel Speed-Step enabled and, as it makes a big difference on power consumption and heat build up, I want to keep it that way. Now, the ASUS board I use seemenly overclocks by upping the turbo boost frequency rather than the base clock. However, in the EFI/BIOS I've set the base clock up to the 4.5GHz, using the aformention settings and as you would expect, turbo boost is disabled and Speed Step manages the clock speed depending on the load. I've had it with the Turbo boost only overclock too.

So, why does the CPU switch between 4.5GHz and 3.3GHz after a few minutes of full load? Temps are good (max is ~65 degrees), stability is rock solid, thermal throttling has been disabled and the issue still remains. And Ideas?

Also, just to make sure that it isn't a problem with CPU-Z, does anyone know of any software that monitors and records your CPU clock speed. That way I can get a better idea on whats happening.

Any idea's would be greatly appreciated.... now to install that 8GB RAM (just arrived as I was typing this)

Chris.
 
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