CPU Fsb Question


Jan 28, 2004
hey guys, I was question about The Newer P4 motherboards and older P4's, are the new mother boards with a 800 fsb and hyperthreading Still able to run a 1.7 P4 with a 400fsb? the reason i'm askin is thats the proc i got now on a board with 1gig of pc133 ram, and i have some money to upgrade with but not enough to get new ram/mobo/P4 so i was hoping to upgrade my ram and Mobo this month and maybe THe proc next but I want to make sure my Old P4 will work, Your Help IS apprecated


Jan 15, 2002
That depends if your 1.7GHz CPU was based on the obselete Socket 423 or the actual Socket 478.

A 423 pin CPU won't fit in a 478 pin Socket (duh), you also need to keep in mind that your PC133 memory won't fit in a DDR socket (duh) and that your 1.7GHz CPU is meant to run on a 100MHz FSB (400QDR bus) with a locked 17x multiplier, meaning that running it on a 133 or 200MHz FSB (533 & 800 QDR bus) will result in a huge overclock.

Unless you decide to run your memory asynchronously (3:4 or 1:2 FSB:Mem factor) your current CPU will most likely fail the POST, causing your computer not to boot or if it do get past the POST, it will behave erratically, run unstable or catastrophically fail, causing permanent damage to the core.

If you are carefull and stick to a 100MHz FSB, nothing wrong will happen, just that your old CPU won't use more than half the bandwidth your motherboard northbridge can provide.

BTW, Intel will soon relase its Socket LGA775 platform, along with the new BTX form factor, DDR2 and PCI Express, making your brand new Socket 478 motherboard a dead end, unupgradable platform due to Intel's decision to stop the Socket 478 line of P4 @ 3.4GHz.

A LGA775 platform will be required if you want a P4 faster than 3.4GHz (unless you choose to overclock).

Fok Speling Misstake