PC DDR RAM question...

[Don]

I used to have 2x512 DDR RAM (PC3200) running at dual-channel 400 Mhz. I recently bought two more 512 DDR RAM sticks @ PC3200 to double my memory to 2 GB. When I installed it, my system BIOS detects 2 GB of memory but running at 320 MHz instead of 400 MHz. When I get into Windows and run my diagnostic software, it detects that I have 4 RAM modules, all detected to be PC3200. What happened? Is it because my latter 2 RAM modules are not the same brand as the first 2? Is there some limitation where using all 4 slots slows down overall bandwidth?

Thanks

 

[hunter001]

If you system picks up slower memory it will clock the memory at the slowest sticks. The sticks maybe miss labeled.

IF not check you motherboard manual to see how it handles memory. Some motherboards have a max memory speed. Yours max might be 320 MHZ.

 

[Don]

Thanks for the reply. My MB max memory speed should be 400 Mhz. And when I ran before I added more memory, my memory was running at 400 Mhz.

I also ran a SW that checks the speed of each DDR module. All four are detected as PC3200 (400 Mhz). So they *should* be all the same speed...

 

[tboy]

I'd also check the mobo specs because I've read that some mobos require 1 or 2 gig modules instead of 4 512's.

Have you tried to manually set the memory speed in the bios?

Also, what manfacturer is the second set of ram modules? Please tell me they aren't kingston or house brand.......

BTW: them being different makes will affect your performance. Whatever I've read on memory it is always highly reccommeded that not only do you get the exact same type, but the same manufacturer.

 

[hunter001]

You might want to check you motherboard manufacturer's website for any firmware patches for memory. They may have found a problem after you purchased your motherboard.

 

[osanowo]

I agree with hunter001. It would be my first recommendation although you must read instructions carefully before flashing your bios.

A safe verification would be to check in depth the integrity of your mem sticks and hence I strongly recommend you the use of that little software:
memtest

Basically you burn a cd and reboot the computer. It will run thorough tests on your memory before windows starts and will tell you everything you need from the format to the fitness tests.

Hope that helps

 

[Don]

Thanks for all the advice. I was able to "force" DDR Frequency to 400 Mhz by tweaking the FSB : DRAM ratio in BIOS. It was set to the default "Auto" which then decided to automatically use 5:4 and explictly set it to 1:1 (which made my DDR run at the max 400). But the fact that "Auto" was using 5:4 bothers me since before I believe it was 1:1 before the upgrades. Oh well. Hope I don't run into any problems.

Thanks again all.