Apr 8, 2011

AMD motherboard stability issues with DDR3 (XMP based memory)

Im building a new computer with the following components:

Gigabyte GA-880GM-UD2H motherboard
AMD Phenom II x6 1055T processor
Gskil F3-10666CL9D-8GBXL (2x4gb)
Antec 650w PSU
HIS 5670 Video Card

I wanted a AMD 880 board and while picking the RAM, I noticed that some of the RAM were marked as specifically designed For 2nd Generation Intel® Core™ processor. It kind of put me off, but I kept wondering why it should make any difference. I assumed it is a Intel muscle at work and moved on. In short, since AMD cannot take more then 1333mhz DDR3, I stuck to the Gskill as it was advertized to run 1333mhz at 1.5v.

Assembled the comp, everything is stock, brand new, basically nothing is OC'ed. RAM settings are 9-9-9-24, 2T DRAM Freq 669.6 mhz and CPU Freq 2008.9 mhz. I put the system together, it booted first time no problem. I installed windows and then I started getting random BSOD's. The BSOD's indicated memory issues, so I ran Memtest for hours on both sticks, then each stick and there were zero errors. The memory always passed on any test I threw at it. But Windows would randomly freeze, the ATI drivers would restart randomly, basically it was hell !!!

Temps were fine for the entire time, and since I was not OC'ing anything, it did not seem like a issue. Everything in the BIOS was left untouched, voltage was stock at 1.50v and timings were stock at 9-9-9-24. I swapped the sticks between DIMM's, reseated them, etc - nothing seemed to work.

I then ran Prime35 and it would fail in a matter of seconds with a warning that there are rounding off errors. Folks on the net say that this means that the CPU or RAM is malfunctioning, which leads to data corruption and hense rounding off errors.

Frustrated, I started reading more stories on the net, then I noticed something fishy. Few other people had similar issues with AMD and DDR3 memory with support for Intel XMP (Extreme Memory Profile) and almost all of them RMA'ed the memory and got different brands. A little research pointed out that XMP allows the DDR3 and the motherboard to exchange information on what speed was necessary and how much voltage was required. On a AMD board, this information exchange was lost.

So I bumped up the voltage on the RAM manually by 0.05v and the Bios showed that the memory was now getting 1.65v. Rebooted, reinstalled and bingo, the system is now as Stable as stable can be. The Ram heats up a little, so I needed another fan blowing air on the sticks, but otherwise everything works beautifully. Prime35 ran for hours and no errors.

Moral of the story, if you buy DDR3 meant for Intel, it means that the sticks use XMP. It also means that AMD boards might not necessarily provide it the correct voltage to run at the rated speeds. In my case, GSkill claims a 1333mhz at 1.5v, but the sticks require 1.65v to be stable at that speed. So do not leave the Bios voltage at default and play around a little if you have stability issues.

Hope this helps someone facing similar issues :-)