I have 2 x 256 mb sticks of slower RAM in my computer and 1 x 1 gb stick of faster RAM. I was just curious as to how the computer treats RAM of different speeds. Is it possible that I could be losing some performance because it is reading/writing to the slower ram when it could be reading/writing to the faster RAM? Or does it use the faster RAM when it's available? Or something completely different? I'm not having any problems with my computer or anything; I'm just curious.

The speed of the ram is usually all the same and is set either manually, or by the speed of the chip. So say you are running your chip bus at 400mhz, then your memory will run at 400mhz. So, you may just be overclocking your slower RAM, or just underclocking your faster RAM.

most likely you are underclocling your faster ram. unless you manually set your memory timings and clock.

Agreed.

If memory timings are set to auto, the bios will read the SPD of the memory and set the overall memory speed to the weakest link...the slower memory. So for example, if your big stick is PC3200 and your smaller stuff is PC1600, then all of your ram will run at PC1600.

Now if you set your mem speeds manually, SPD will be disregarded and your motherboard will attempt to run all memory at the same speed that was manually set. So if you have the same stick of PC3200 and smaller sticks of PC1600 and you set your mem speed to 200MHz, then when you boot...you had better have the best PC1600 on planet Earth.

IBM Microchannel and CBus were the only things I could remember that did multispeed ram. Amazingly flexible, but most operating systems wouldn't run stable with it.