i have four dimm slots and four sticks of ram 1 x 64mb pc100 1 x 64mb pc133 1 x 128mb pc133 1 x 256mb pc133 does it matter which order they put into slots.

Using the pc100 dimm defaults the 133's to 100. I would get rid of the 128 and the 64's and get another 256. got to UBID, sell what you got use the funds to buy the 256. leave your other slots open for now 512 is plenty. If your keeping it put the biggest chip in the first slot second biggest second slot (you see where im going with this right?)

no - but if your machine takes 133mhz, you shouldn't be putting 100mhz cards in(they conflict & it will slow the system down in some cases. ram's cheap so i would throw the card away & make em all the same hope this helps

Some motherboards are rated at 133 and the oem's put 100 in them. then you go out and buy the cheapest ram and it only comes in 133 but the ad says it will work with both and you end up with both. pull the 100 and enter bios. if it shows up 133 eliminate the 100mhzstick if it shows up at 100 your buying the wrong ram. Agree with getting rid of the mismatched sticks. I know it says non parity but ive gotten better performance from a machine with two 64 than a similar machine with 128 and a 64.

Does the order of the RAM effect performance greatly? I have 3 slots of DIMM RAM PC133 128mb PC133 128mb PC133 256 MB Now I recently had to remove the slot of 256 because I was getting Windows errors. Could it be that I need to put the slot of 256 in the first slot and the two 128's behind it???