I am in the process of building a second PC, taking bits outta my new one and putting them in my second.

My questions is:

Can I mix and match memory (RAM), ie. one stick of ddr266 and one stick of ddr400 in th same PC? Or does it have to be the same type / speed?

You can mix DDR RAM but on a few conditions... ALL the system RAM will run at the speed of the slowest installed RAM, so 266 in your case. the rest of your system needs to be in line with the DDR266 RAM so a 3.2g Athlon with a fast front side bus is not a good idea, An Athlon 2200 has a FBS of 266 so should be fine. (I think!!)

Thanks Neeeeeeeeek.

So I need to ensure that I have a CPU with a fsb 400 before I install DDR400 ram ?

Other way round - your memory can run faster than your FSB, but if your FSB is faster than you memory, it will most likely blow. Yes, that is from experience :(

So if you think you're going to upgrade soon, it *may* be worth shelling out a bit extra on faster memory now.

Not if youre planning on mixing it with ddr266 ram, as all the ram will then run at 266. What neeeeeeeek was getting at was that if you install a cpu with a 400mhz FSB, and use ram thats slower than the FSB, you might run into problems. But, as long as the slowest stick of rams speed is equal to or higher than the CPUs FSB, youll be alright.

Originally posted by slh73
Not if youre planning on mixing it with ddr266 ram, as all the ram will then run at 266. What neeeeeeeek was getting at was that if you install a cpu with a 400mhz FSB, and use ram thats slower than the FSB, you might run into problems. But, as long as the slowest stick of rams speed is equal to or higher than the CPUs FSB, youll be alright.

Yep, I pretty much get it thanks.

I won't mix the ram, will just use DDR400.

But if my CPU has a FBS of, say 266, would I be just as well using DDR266 ram !? (i.e. it would be a waste to use DDR400 ram with a CPU that has a FBS of 400?).

Technically yes it's a waste but its for the difference in price it's not really worth worrying about. Certainly not worth selling the 400 and buying some 266 anyway! Either get a A200 athlon and use it all or get a faster Athlon and flog the 266 RAM.

Youll probably find that ddr400 is cheaper than ddr266 and 333 anyway.