Running 1866Mhz Ram on Athlon II X4?

[dostov]

So... I bought this RAM: Vengeance Pro 1866Mhz 2x4GB 9-10-9-27

I was expecting to achieve 1866Mhz at rated timings on my AMD Athlon II X4 635. Seems like it won't be that easy.

Now the said CPU natively supports up to 1333Mhz RAM, but with my previous set of RAM I could achieve almost 1600Mhz without touching any voltages (234Mhz "FSB" on 1:3.33 mem ratio). By using a low RAM ratio I can easily OC this CPU to 3.4Ghz (234Mhz x 14.5 multi). But if I try with the 1:4 ratio I just can't go past 210Mhz on the "FSB", resulting in RAM speeds of 840Mhz (1680Mhz effective), and a pathetic CPU OC of 3045Mhz. I was totally hoping for my 3.4Ghz OC and 1866Mhz RAM on this setup.

My best guess is this is caused by the IMC in the Athlon II... right? If so, is there any chance I can have my RAM at its rated speed and timings with this CPU?

By the way, mobo is MSI NF980-G65

Any help would be greatly appreciated!

 

[Woomack]

It's not always easy to set higher memory clock on AMD other than FX series.
I'm not sure how it's related but when I had FX8120 then I couldn't use higher FSB with some memory kits. It was like on one kit I could make 300FSB stable but on the other memory, board didn't want to boot above ~225MHz.

I would try some timings manually like 300-350 tRFC, always command rate 2T/N and something like 9-11-9-27 / 9-11-10-28. Also add some CPU-NB voltage like +0.1V.

 

[dostov]

Will try that. Thanks for the advice Woomack!

It's a been a while since I tinkered with this system. It's my main work computer so I can't really afford to bork it.

 

[dostov]

Been playing with it for half-an-hour now. RAM just won't run over 1720Mhz or so... I think it's my CPU IMC limitation. I settled on 1666Mhz (250x3.33) for now in order to get my CPU back up to speed.

Oh well, I'm gonna have good RAM for when I upgrade MB and CPU later on.