Uncore:QPI ratio?


Jul 18, 2009
I've been looking at all kinds of guides.... and some are saying that having a 8:9 uncore to QPI ratio is important

My Current set up is:

i7 920 D0 @ 3.8GHZ (181 x 21 CPU) @ 1.20625 Vcore
CBLK @ 181
DRAM @ 1810MHZ 8-8-8-24 (2:10) @ 1.64V
uncore @ 3620MHZ (CBLK x 20)
QPI @ 3258 ((CBLK x 36)/2)
QPI/DRAM @ 1.375V

Prime95 Small FTTs with RealTemp

Core Loads @ 64C Max @ Ambient 25-27C

Now I am running into this problem, I am unable to get my System to post at all when I select QPI at a Ratio of ~ 9 to the Uncores of 8,
if I was to follow the rule to achieve stability.

How Important is it, to keep the Uncore to QPI ratio of ~ 8:9?
Is there any evidence of reduced system performance of running Uncore higher than QPI?

I have had this setup runningfor the past 2 days, and have not encountered 1 problem so far. It passed numerous intel burn test of
20 passes @ 1024MB and 8 threads.

Reason why I bench with intel burn test, it seems to find instabilities in 4 passes or less (@1024MB RAM usage, each pass is at about 17-18seconds),
where as prime95 would never show one, even after of 13+ hour runs, both at same system settings.


Feb 14, 2009
Im assuming you read my guide on toms hardware?

The QPI step is not crucial. If you dont do it then it may require a little more QPI or uncore voltage. But that is not a problem.

I can achieve 4.53 without adjusting the QPI ratio at all.