I have the Asus P4PE-BP MB, which has 3 ram slots. For a long time I had 2 ram chips that worked fine. I just tried to add a third ram chip, but when a third one is added, the computer wont boot. I've tried several different types/sizes of chips. I've also tested each ram slot individually (and they all work). So basically, this is what it comes down to.... - It doesnt matter what type of ram I use, or which 2 of the 3 ram slots its it. Any 2 slots work fine. But as soon as I add ram in the last empty slot, regardless of which slot that is at the time, the computer wont boot. My brother just built a new computer and the USB connector on the front of his case had a built-in wire for a pin the mboard indicated should have NC. Until then his 2 USB ports wernt working, as well as one of his IDE slots. He just pulled the wire out and now everything works fine....but checked on my system and doesnt seem to be a problem. Any thoughts? thanks

Check your manual for maximum Ram capacity.

Not necessarily RAM capacity, but how many banks. Generally, each DIMM slot is comprised of 2 banks...so your's should have 6. A double sided DIMM uses two banks...single sided uses one. But there may be a limit on how many banks can be used on your board. This is strictly a guess, but your's is probably limited to 5 banks. You should be able to fill all 3 DIMM slots, provided one of your DIMMs is single sided...

Good call Jam. I checked out the manual on Asus' site, and says there that if all 3 slots are filled, only one of the chips can be dual-sided. Thanks......and if anyone can explain....whats the difference between single/double sided? which is better? difference in price?