Is Pentium 4 cpu 800fsb O.K on 400FSB?

Hi

Just wondering if its possible to use a pentium 4 cpu / 800 bus to use on a P4 400 Bus mobo. The replacement cpu speed is 2.6GHZ, and is supported by a mobo that i would like to upgrade. However the Front side bus on the replacement 2.6GHz cpu is a 800 Bus - the mobo only supports a 400 Bus.

Scenario,

Recovered a P4 2.6GHz C.P.U (from a failed Dell Gx) with 512K cache / 800 Bus (cpuid = 00000F29) if this helps.

Trying to install this cpu in a Asus P4SGL rev 1.03 Motherboard. The online motherboard manual suggests it supports a cpu of this speed although the bus potentialy is the issue. Only found out the 2.6GHz bus issue when inspecting the cpu and cleaning away thermal paste, the bios auto configures this at about half that speed @ 1300.

Is the cpu speed an issue because of the bus? being half the speed?
Is it possible to underclock - or use the cpu 2.6GHz 800MHz bus cpu on a 400MHz mobo.
Reason is the original cpu is only a P4 - 1.8GHz bus @ 400MHZ and would just like the faster speed cpu.
I appreciate I cant potentialy do anything about the mobo's bus itself.

Should i update the mobo bios..first thought i think probably not? if any one has done this and had no issues, could you please let me know.

Normal day to day cpu issues i deal with are at home..heh.. but those are AMD's so a little but unfamiliar with the Pentium settings...I'm aware of antistatic etc..procedures so no worries there..

//thanks in advance
l8r world:wave

 

Yes. Because you're running a CPU with an 800fsb on a 400fsb motherboard, you will only get half of the true CPU speed. You can try overclock the bus if the BIOS has options for this. You should be able to get the bus speed overclocked as high as the motherboard allows because you are not limited by the CPUs FSB.

Research the motherboard and updated BIOS releases at the manufacturer's web site. If a BIOS update's description says that the particular update addresses FSB and/or new CPU compatibility, then it may be worth it to flash the BIOS. Regardless, you can run the CPU at half-speed indefinitely without any negative effects, but a replacement motherboard that fully supports the CPU is only about $50 (for example, look at this board; socket 478, 800fsb, DDR2, with PCIex x16 video slot!).

 

Cheers for clarifying this for me, thanks yet again dlb.