going over FBS (upgrading)

For some reason i found a processor with 533MHz FBS that is cheaper then one that is 400MHz. I have an old system i'm upgrading and I was wondering, if the frequency was the same, and my motherboard only supports 400MHz, would my motherboard be bottlenecking it, so the 533MHz would work as a 400MHz?

If you can't manually adjust the FSB to 133 MHz in the BIOS, then your 533 processor will only run at 100 FSB. For example, a 2.4B 533 bus P-4 will run at 1.8 using the 400 bus. What motherboard fo you have?

old one, on my old system, asus P4B266 with onboard lan & audio, supports 400MHz i think

You might be in luck. That was a good mobo back in its day and it does allow FSB adjustments. Check out this article (see link), they were able to run 133 FSB, you'll just have to set it manually like you were overclocking.

http://www.lostcircuits.com/motherboard/asus_p4b266/

that looks very long and confusing.. I'm not to good at overclocking, im kinda new to it. I'll try reading it and doing what i can, but i am going to buy the CPU soon and I need to know if it will 100% work... will extra cooling be required? Am i overclocking my motherboards FBS? i didnt know you could do that... by the way the CPU is 533, the mobo is 400... Really confused, but less than before
Much thanks this far

haha, i was like what is fbs?

I responded to your PM, but I will also post here in case other people in the same situation are trying to figure this out too. The system bus speeds of Intel and FSB (front side bus) speeds are a little confusing.

Ok, 400 and 533 is the system bus speed because P-4 systems use a quad pumped system bus. But, 100 FSB X 4 = 400 system bus and 133 FSB X 4 = 533 system bus. For example, a 2.4B is a 533 bus processor. It uses a 18X multiplier and 133 FSB (18X133=2400 or 2.4 gig). The rest of the chipset runs at 533 bus speed, but that is not used to figure processor clock speed. So, 100 FSB is the default speed of 400 bus CPUs. If you put a 533 bus CPU in your motherboard, it will probably run at 100 FSB by default. So, that 2.4B will run at 1.8 gig unless you manually set the FSB to 133, then it will run at 2.4 gig. Make sense now?

A 533 bus CPU will work in your mobo, worse case is it will run slower than advertised speed. Looks like you can manually set the FSB to 133 to make it run at it's normal speed. That is what we do to overclock, we raise the FSB to make the CPU run faster.