DDR2 533 and DDR2 800 on same MOBO?!?!

[furrevig]

i currently use AMPO 512MB 240-Pin DDR2 SDRAM DDR2 533 (PC2 4200) System Memory, and im getting another stick.

im thinking of getting CORSAIR XMS2 1GB 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Desktop Memory


my question is, can i run those two sticks on the same mobo without problems?

since one is 533 and the other is 800.

 

[Mondoman]

All the memory on your MB needs to be run at the same speed, but there is no problem running RAM at a *slower* speed than it is rated for. In your case, all your RAM will run at DDR2-533. Unless you are planning on using the DDR2-800 RAM for something else in the near future, you will likely save money by buying DDR2-667 or DDR2-533 rated RAM instead of buying DDR2-800, since you will be running it at DDR2-533 anyway.
The other issue is running in dual-channel vs. single-channel mode. Running in dual-channel mode will double the memory throughput and probably help improve performance 5-10% overall, depending on the rest of your system. However, in order to run in dual-channel mode, you need to have pairs of identical (same size, speed, and internal organization) DIMMs, along with a MB that has dual memory controllers. Just about all MBs that take DDR2 will have dual memory controllers, so I would suggest selling your current 512MB DIMM (maybe on eBay) and buying 2x 512MB or 2x 1GB DIMMs for your system. As an added benefit, the new modules would be rated at the same speed, so you could run them at their (higher) rated speed rather than having to run everything at the DDR2-533 speed of your current DIMM.