Received new RAM today. My dad's PC now has 2 sticks of 512 in one bay and 2 sticks of 512 in another for a total of 2GB, however its only showing 1.7GB and says 'Memory runs in Single Channel' or something similar when it boots.

Also, now my PC has 2 sticks of 1GB in one bay and, in the other bay, a 1GB stick and a 256MB stick, but its only showing 2.18GB (which is funny b/c before I had 1G, 1G, 512, 256 installed and it showed 2.7GB).

Any ideas why the PCs are showing less than what's actually installed? I know you have to match certain things in the same bay - however, I'm unsure whether that's size/speed/or what.

Thanks for all helpful responses,

Dear Soer, the first thing you must do is make sure the speed frequency of your RAM matches the frequency of the front side bus on your mother board. You can find this information in the motherboard manual or use software like cpu-z or sandra which will provide you with a wealth of information. Also, make sure that you are within the limit of how much RAM your motherboard can support! Older motherboards will support up to about 2GB RAM and the rest is useless. New motherboards can support up to 16-32 GB of RAM. For your dads PC i think the RAM may be single channel RAM (DDR) if its not and its dual channel (DDR2) then there might be a bios setting to change it OR your motherboard might not support dual channel RAM OR the RAM might be faulty. In any case i suggest you contact the manufacturer of your motherboard and whoever makes the RAM. I think the same applies for the RAM installed in your PC. Best of luck.

OzY360, thanks for your response!

When you say FSB speed, is that the 300 vs 400 or would it be more like 2000mhz? The RAM Chips dont say any speed other than 300 and 400mhz.

I found out the issue with my dads PC. I booted up with each different chip by itself. One of the 512MB Kingston chips is only showing up as 256.. is that really possible that half the chip is defective? Do you know if Kingston has a warranty policy?

I'll let you know how it goes with my PC.

Thanks again - very helpful!

Yes your right about the FSB - the value is usually in mega hertz (Mhz). Its very possible that the 512MB Kingston RAM is faulty or it may not be compatible with your motherboard. I suggest you get in touch with Kingston and they should replace the RAM since its a manufacturing fault or maybe you bought the wrong type of RAM, not knowing any better. Always ensure the product is 100% compatible before buying it. If the RAM had been generic you might have not been so lucky in having it replaced! Best of luck.