compatibility question for p4, plz he (intel newbie )

[hoomza444]

i have a friend who has some pc800 rdram. he is thinking of getting of setting up a new p4 rig and asked me something, that caused some confusion.

is a p4 fsb locked? or is it the multiplier? he wants to get a 533 fsb p4, but his ram is pc800, and he wants to make sure it's compatible? he said that since the fsb is locked, the 533 wouldn't be compatible to run at a lower setting like 400? i said that there should be a seperate setting for memory and cpu, and even if not, that it would still automatically run at the lower speed. but he said that since the FSB is locked it wouldn't downgrade. so i don't really know what to tell him, i only know about AMDs and havn't touched an intel cpu in over 5 years. i had always assumed that the multiplier was locked and that the FSB could be changed, but my friend said that on the p4 is different.


anyway, without blabbing.

1. is p4 locked by fsb or multiplier? how is it overclocked? do the boards have sepearate cpu bus and memory bus settings?
2. if it is locked by fsb, will a 533 fsb run at 400 mhz despite the locked multipler? i.e., will it run with pc800 ram? or would the ram need to be upgraded to pc1066?

thanks in advance!

 

[bgeh]

1)the p4 is locked by multiplier.the fsb and memory bus are related by the memory ratio.
2)it will run with pc800 ram but you will see a performance hit

 

[Mikki]

Originally posted by: bgeh
1)the p4 is locked by multiplier.the fsb and memory bus are related by the memory ratio.
2)it will run with pc800 ram but you will see a performance hit

...how can it be a performance hit if he's upgrading his cpu? :Q

 

[hoomza444]

cool, sounds good, thanks alot.

 

[RanDum72]

...how can it be a performance hit if he's upgrading his cpu?

Probably he means that its not as fast as using PC1066, which runs synchronously with a 533mhz FSB. Also, some RDRAM boards won't run CPU's with 533FSB with PC800 unless the latency is rated 40ns. There are some PC800 thats rated at 45ns.