Paired RAM

[StraightPipe]

i started with 256 (pc2100) and almost immidiately added a 512 card. I was very happy with the increase. very noticable difference.

now i have 512 in 1st slot and 256 in 2nd. the system shows 768, I wondering if the mixing hurts me at all. it's definately better than just 512 right? is it worth another $100 to have another 512 card shipped to replace the 256?

what about 512 pc2700 to replace the 256? does it hurt to mix 512pc2100 + 512pc2700? would it be better than 2X512 pc2100?

 

[Xentropy]

While it doesn't literally hurt anything to use memory with different timings simultaneously, the entire memory bus runs at the same clock, so PC2700 running with PC2100 would just mean that both sticks would run at the speed of the slowest.

Running two memory sticks of differing sizes is meaningless UNLESS you're using a chipset that supports Dual DDR, which will only use the dual channels if both sticks are the same size. We'd need to know what motherboard (or at least what chipset your board is using) to tell you that.

 

[StraightPipe]

845PE from dell (4550)

 

[StraightPipe]

It says with DDR support. is that it then? my 768 is good?

 

[Lord Evermore]

Your setup right now is functional, but not as good as it could be. You might get better performance with only the 512MB of PC2700. Right now your memory is probably running at PC2100 speeds. The Pentium4 needs a lot of memory bandwidth to perform well. If you remove the 256MB, then the 512MB module should run at PC2700 speeds by itself. The extra memory bandwidth might make a bigger difference than having more memory total. You can check the specifications of your machine at Dell's site to be sure it will run PC2700 (333MHz) memory, which it should since it uses the 845PE chipset.

Using different size modules does not affect a single-channel setup at all. Dual channel accesses both modules at the same time, so you need to use the same type of module in both slots for dual channel (but it's apparently not required with the nforce2, it just works better that way). The 845PE is a single channel chipset, so the size of the modules isn't anything to worry about, only the speed.

I checked for you. The motherboard will automatically run at PC2700 speeds for memory if you only have PC2700 installed, and if your P4 uses a 533MHz frontside bus. If you have a 400MHz frontside bus P4, then the memory will only run at PC2100 speeds (the BIOS setup has no options to change the speed manually).