-----Original Message-----

Date:    Tue, 16 Oct 2007 11:12:18 -0700
From:    Glenn Goodrich <[log in to unmask]>
Subject: Pentium 4 FSB question.

I have a Compaq computer that uses a socket 478 Pentium 4 1.7 GHz processor
with a 400 MHz FSB. I want to upgrade this processor, and I have found 2.8
GHz socket 478 P4, but it has a 533 FSB. Will this processor still work,
just at the 400 MHz FSB speed, or are they completely incompatible? Is there
a way to find out the speed it will run at with a 400 MHz FSB?

Thanks

Glenn Goodrich


---------------------------------
Tom's Hardware has a couple of good comparison charts that detail Intel and
AMD processors. The P4 you are looking at with a FSB of 533MHz acheives that
speed with a clock multiplier of 21 (21 x 133). Your motherboard supports a
"Quad Data Rate" FSB speed which is 4x100 for 400MHz. (The other chip
supports a 4x133MHz data rate) If you do get that chip, it will run at a
slower clock speed as the multiplier is locked by Intel. (21 x 100 = 2100 or
2.1GHz)

Intel does make a P4 that supports a 400MHz FSB. It has a multiplier of 28
(28 x 100 = 2800) There are a number of "Northwood" named chips from Intel
that support a FSB of 400MHz in speeds that range from 1.6GHz to 2.8GHz.

The other aspect to consider is the supported voltage your mobo supports for
the CPU. I'mn guessing your current chip is a "Williamette" which requires
1.75V whereas the "Northwood" needs only 1.5V.

The "Williamette" series of chips has clock speeds up to 2.0GHz.

HTH and happy hunting.

Chris Ryan

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