Mobo/CPU/Memory Spec Confuzion...

[Baphomet]

Okay, so can someone explain something to me, please? I'm on the verge of uprgrading my current PC (new proc and mobo) but am curious about the relationship between the FSB of the motherboard, the CPU FSB and Memory speed.

 

For instance, if both the CPU as well as my new Mobo's FSB are set to run at, say, 400Mhz, but my memory is running at 266Mhz, am I crippling my overall performance??

 

Would it be best to have everything running at the same speed? Is one FSB more "important" than another for getting the best performance? For instance, is it better to have a screaming mobo FSB even if the CPU's is slower or vice versa, or would be better to have faster memory regardless of the CPU and/or motherboard? Am I making sense??

 

Any clarification on this stuff would be appreciated.

 

Thanks!

[drowst]

The short answer is yes. In a current p4 for example, you are running on an 800mhz bus. Your memory is running at 400mhz, but since it is "double pumped" it has an effective speed of 800mhz, matching the bus speed. You can put slower memory in, and run at different speeds, but this will effect performance. If your buying a current p4, you'll want to get pc 3200 ddrsdram for best performance. The bus and processor speed are linked. My box for example is an athlon 2400 with a 333mhz bus. I can't go to a faster proc on the mb due to the bus speed. I would need to go to an mb which supports 400 mhz if I wanted a newer athlon. I could overclock the processor by raising the bus speed and/or changing the multiplier, but that opens a different can of worms. The question comes down to whether your planning on buying a pre-built box, in which case your going to get whatever they sell you, or are you wanting to build your own. If you want to build your own, you need to decide what proc you want to run, find a motherboard that supports it, and then buy memory that matches the speed recommended for that board. You can always use a slower proc or memory than the max the board handles, but you'll take a hit on performance either way. Ultimately go with the fasted proc and memory you can afford and don't worry about the bus speed, as it will adjust itself to whatever proc you plug in. Sorry about rambling around, I hope there was a worthwhile tidbit in here.