xp64 cant see my 4gb ram

Hi,

Just installed 2 x 2gb Corsair 4096mb twinx xms2 6400 ddr2 ram in my Asus P5kpl mobo, q6600 CPU, running XP64. Updated to latest bios. Only 3.5 gb of ram is recognised, and running Benchmarks it is slower than when I had XP32bit installed. Any ideas would be good.

This is a common problem with people that have 4gb of ram.  You have to disable the memory remap in your BIOS, in the Advanced Menu -> Chipset -> North Bridge Configuration.  Then choose the Disable option for the Memory Remap Feature option.

Now I am really confused. went into bios and found Memory remap feature was already disabled. So I thought I would  enable it to see what would happen. Now the system genneral tab shows the full 4gb. Now going to run Benchmarks again to see if there is any difference.

Ah, my mistake.  Yeah, I wanted you to toggle whatever setting was there :).  Basically, every manufacturer has a different way to control this in the BIOS, so on another board it might be opposite.

I looked up your mopther board on the Asus web site and I lifted the following information: 

"When installing total memory of 4GB capacity or more, WindowsR 32-bit operation system may only recognize less than 3GB. Hence, a total installed memory of less than 3GB is recommended."

It also said something about using all four memory slots over 2GB?

I know you said that you have the 64 now but though it intersting and wondered if it is a glitch of that MB with 64 OS also. I would consider writting to Asus. 

You might want to check Corsair's website for what is recommended for that motherboard. Maybe the memory is not the right one for that motherboard.