Get Stable with 8GB RAM?

pswfps · 22 Feb 2010 at 20:16

Hi, I've been running my system with 4GB for a while now and have just acquired a couple of new DIMMS to take the system upto 8GB. Here are the memory specs:

Original DIMMS: Kingston 2x2GB HyperX DDR2 1066MHz 5-5-5-15 2.2V
New DIMMS: G-Skill 2x2GB DDR2 1066MHz 5-5-5-15 2.1V

Unfortunately I'm having problems getting the system stable with all 4 DIMMS installed. With either set of 4GB installed, the Kingstons or the GSkills, the system is completely stable running with VDIMM 2.2V @ 2T, ie memtest and prime95 blend report no issues. With all 4 installed Pr95 and memtest find issues pretty quickly.

Is there anything I can I do to remedy this?

Thanks in advance.

Corasik · 22 Feb 2010 at 20:23

As your already at the upper voltage limits, then slackening the timings is the next best option to try.

pswfps · 22 Feb 2010 at 22:13

Just tried slackening off timings. Results:

6-6-6-18 - still unstable Pr95
7-7-7-18 - fails to POST

That's about the slackest my mobo will allow.

hawker1986 · 22 Feb 2010 at 23:01

Try giving it an extra 0.1v to the northbridge. May help

Hawker

pswfps · 23 Feb 2010 at 18:45

Sadly not.

However, I decided to drop it down to DDR2 800MHz and the 8GB seems stable at this speed. Early days yet but been running 3 instances of memtest without issue for an hour now!

Have been reading around the web and it seems that mobos are often unable to run higher amounts of RAM at the same speed as lower amounts. Looks like mine struggles with 8GB @ 1066MHz and needs to step back a bit.

I might be able to get something back by upping the system reference clock and tightening the timings.