I have an asus K8VSEDX motherboard.

http://www.asus.com/products/mb/socket754/k8vse-d/overview.htm

Why are two RAM slots yellow, and one is blue?

I ask because I bought a 3rd RAM module a while back, and whilst it was PC3200 DDR 400mhz it was a different manufaturer than my other RAM.

Should I put the newer Ram in a particular place if I feel it hasn't made much of a difference to performance, (perhaps even a drop?) in say 3dMark or particular RAM greedy games. All strips are 512mb.

Those should be for different ram types.

I have not seen a PC that would work with different types at the same time.

Do you see all of the ram on power up?

I suggest you grab your motherboard manual and check out the Memory configurations section, notably the Recommended memory configurations table.

Yes, in many instances where two slots are on colour and the third slot another, it will be because two specific slots need to be used either for dual-channel configuration or for using modules of different sizes together.

For this mobo, I dont think it is for different RAM types. In the specs it says:

3 x 184-pin DIMM Sockets support max. 3GB un-buffered ECC and non-ECC PC3200/PC2700 / PC2100 DDR SDRAM memory

Then it will be for a reason such as I outlined.

Thanks, for the replies. I have the same type of RAM, just different manufacturers.

Don't have a manual, will download when the site works.

Thanks Catweazle for your advise, suppose should of just got the manual to start with, guess I thought it would be generic for every mobo.