New
#1
Issue 1: DDR2 pairs don't play nice together, why not?
I have a custom built Asus M4A875-M system with a 2.4Ghz Phenom quad core CPU. I bought 8GB more DDR2 RAM to max out my system to 16GB but the new RAM won't play nice with my existing 8GB RAM at it's rated speed.
My existing RAM is the Silverline from Mushkin. pc2-6400 / 800Mhz. It runs in either ganged to unganged mode just fine when it's plugged into slots A1 and B1.
I can likewise plug in the new memory (2x4GB bought on Amazon, Ninix) into slots A2 and B2 and it runs at 800Mhz just fine IF I REMOVE THE MUSKIN memory. It will not run if both types are plugged in AS DESCRIBED.
I can run ALL of the memory if I run one type in slots A and the other type in slots B, HOWEVER at a slower 667Mhz not 800Mhz.
All of the BIOS settings are in the AUTO position.
The Mushkin memory is labeled 6-6-6-18 an is 1.8 volts.
The Ninix? is labeled 666-12 and I don't know the spec details. Bought on Amazon
I don't understand why the BIOS is unable to configure the slots to run at their max speed, when that mobo has fine grained control of the clocks and various timing settings independently for each slot. I don't see a separate voltage setting for each slot or bank though. I learned that the unganged mode is the best way to go, especially with a quad core CPU.
I hate to sacrifice the performance boost that 800Mhz gives me over 666Mhz, but I also hate not being able to use the additional 8GB.
If the Amazon add said the RAM was coming from China I probably wouldn't have bought it, but I see that brand in many systems so it's not like it's no name. However, many products from China on Amazon are fallouts / substandard, so this trouble is not shocking. Yet, as it does run at rated speed when it alone is in the system it makes me wonder if I could tweak the BIOS using custom settings to get them both to play nice with each other at 800Mhz.
There are like 10 -15 individual RAM timing parameters, and I have no idea how to set them. The fields don't get populated with values when switched from AUTO to MANUAL, one has to know what values to use.
If anyone has insight into how to resolve this I'd love to hear from you. I have 2 other issues, so thought I'd post this one here while I was at it. This one might be best answered at Tom's hardware guide, but we'll see, I'm the optimistic type.