I have an ECS P4VXASD2+ (V5.0) motherboard, which supports a 533 MHz FSB.

I want to put in a Pentium 4 3.2 GHz processor (Socket 478) with an FSB of 800 MHz.

Would this be possible? Would the FSB of the processor just be limited to 533 MHz?

2 Answers 2


There are no CPUs that run on a 800MHz FSB that are on the compatibility list for that motherboard as far as I can tell. This usually means that the computer will not POST with the unsupported chip in.

Occasionally a motherboard will boot with an unsupported CPU, but I would be very cautious as this is usually unstable. In this case, the CPU would run at 533MHz FSB, which in-turn will lower the operating frequency of the CPU. If you need a primer on how FSB speed and CPU speed are related, you can read my answer here, which describes this in detail.

  • Hi MarkM, From the official website, it says that any Pentium 4 (Socket 478) would work on the board. I'd like to know which ones are actually compatible, so could you link me to that list? And thanks for that link about FSB & CPU speed. However, looking at my eMachines T2482, I see that my RAM speed is also running at FSB speed. However, PC1600 (200 MHz) and PC2100 (266 MHz) are supported. Still, it runs at 133 MHz (my max FSB). Is there a link between those?
    – Wesley
    Mar 8, 2010 at 0:27
  • Oops, just read that only Intel P4s with up to 533 MHz FSBs are supported. Had to download the manual to find that out...
    – Wesley
    Mar 8, 2010 at 0:31
  • Sorry for the triple comment, but does the processor only have to be Socket 478 w/ a 533 MHz FSB to work?
    – Wesley
    Mar 8, 2010 at 1:11
  • It looks like your motherboard only supports 400 or 533MHz FSB CPUs, so if you can even find a 400MHz FSB CPU, then you can put that in (though I see no benefit). As for your question about RAM - RAM has an independent ratio that is used for allowing different RAM and bus speeds. 1:1 is optimal in most normal (non-overclocked) cases as no cycles are wasted.
    – MDMarra
    Mar 8, 2010 at 1:18
  • ecs.com.tw/ECSWebSite/Products/… is the link to the specs where it says only 400 or 533MHz FSB CPUs
    – MDMarra
    Mar 8, 2010 at 1:20

Many overclocker-friendly motherboards allow you to manually set the clock frequencies for your CPU. If your motherboard allows this, you should be able to underclock the CPU to a 533 MHz FSB, and either use the stock multiplier or--if you're lucky--get it to work with a slightly higher multiplier. You probably won't be able to get the full 3.2 GHz out of the CPU, however.

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