The solution ...
... is pretty straight-forward: if you intend to overclock the BCLK with the IGP enabled, you'll have to change the IGP offset frequency in the bios if you don't want to run into stability issues. That's the positive news. Sadly enough, there's a lot more involved, it seems, when overclocking the IGP than this article might tell you.
We have noticed, for instance, that changing the QPI frequency can have a negative affect on the stability of the overclock, both when increasing and decreasing. From my notes, for example, I see that the 36x QPI multiplier gave me the most stable results whereas 32x and 40x decreased the stability of the system. In addition, it seems that certain BCLK/IGPclk combinations produce a bit better results in 3DMark, mainly in GT1 which is the most system bound subtest. We suspect that the memory performance is somehow affected by the IGPclk and/or the BCLK. It's possibly not the smartest move to throw in the word "strap", but that's how it comes across when looking at the performance numbers at the bottom of last page. Maybe it's for the best that there's still some oddities ... it's no fun when technology is easy to understand.
Truth be told, I was actually preparing for a much larger article regarding the Clarkdale IGP, mainly focussing on the overclocking part of the story. But, I was triggered to release this smaller article because I wanted to set a few mistakes straight and possibly also because I have a hard time convincing some manufacturers that BCLK is indeed affecting the IGPclk. I think the numbers on the bottom of the previous page speak for themselves: the combination of BCLK and IGP frequency set in the bios are determining the performance of the IGP ... not
the IGP option alone!
I'd like to thank the people from Gigabyte and Corsair for sending me the hardware needed to test this platform, as well as the folks over at Intel Belgium who allow me to do a lot of research using this one CPU. To end with, thanks goes out to Manu from TONES
who's always there to support Madshrimps with the latest hardware!
Also, please visit HWBOT.org
, the worlds largest OC database.