Uncore/Memory Multiplier for Lynnfield

[stealth915]

So from all the X58 overclocking guides, it is suggested to that the Uncore Multiplier be at least 2x the Memory Multiplier. What was the reasoning behind this, and has this "magic ratio" changed with the P55?

The 860's Uncore Multiplier is 18x, and with official DDR-1333 support, a 10x Memory Multiplier. I know most people set the memory multiplier to 8x or lower when overclocking to get high BCLKs while keeping to their RAM's rated speed, but will a 10x or even 12x multiplier even work with the Uncore being 18x?

I'm asking because I can't get my system to be stable at speeds higher than DDR-1066. It randomly locks up on me and I can't figure out why. I haven't overclocked yet, I am just trying to run my i7 860 with the stock 133 BCLK at DDR-1333 and 1600.

Specs:
Core i7 860
Gigabyte GA-P55-UD3R
4GB OCZ Gold DDR-1600 RAM (8-8-8-24)
Radeon 4890

System is completely stable with at DDR-1066 (8x) but not at DDR-1333 (10x) or DDR-1600 (12x). Any thoughts/insight is greatly appreciated!

 

[lopri]

I don't think it's necessary to have uncore multiplier at x2 of memory multiplier, but I could be wrong. In any case, have you tried up'ing uncore multiplier to x19 or x20?

Edit: In the following page of an AT review, an i7-860 runs x18 NB alongside x10 memory.

http://www.anandtech.com/mb/showdoc.aspx?i=3655&p=6

Others might give a first-hand (and better) advice. I'm just going by what I've read. Welcome to AnandTech Forums.

 

[stealth915]

I thought the Uncore multiplier is locked at 18x

I'll take a closer look when I get home. Thanks for the reply!

 

[RussianSensation]

I had the exact same problem with OCZ Gold DDR3-1600 Low Voltage 1.65V on MSI CD53. It would not work without a BSOD at DDR3-1333 or DDR3-1600. Returned both items and replaced with what's found in sig below.

Check that you have increased voltages to 1.65V. Does your ram support XMP Profile? If so Enable XMP Profile1 in BIOS.