Member Avatar for owenbear

Hullo again,

After being given even more old PC bits I now have questions about switching CPU's.


I've tried swapping my old socket 478 1.7Ghz for a P4 2.5Ghz (socket 478).

The motherboard is an ASUS P4B-533VM.

And here begin the problems...(and the questions)!

1) After the swap the PC gets to BIOS then freezes, doesn't accept any keyboard input then restarts and repeats the above.

I've realised the P4 1.7 is 1.75 volts while the P4 2.5 is 1.5 volts (also the wattage is different). Is this the problem or should the motherboard adjust for this?

2) When I removed the heatsink from the 1.7 the CPU came with it and is stuck to the heatsink. Now I cannot reinstall it to it's 'home' motherboard. How can I get the CPU off the heatsink without damaging it. It looks like it's stuck using thermal tape or something. There is a black square around the edges of the CPU which I think is the tape.

3) Should this CPU work in this board anyway?

As always any help/information is greatly appreciated.

OwenBear

More info.

Mother board is: P4B-533VM socket 478
CPU (was) : P4 1.7Ghz L1 8kb. L2 256kb swapping to P4 2.5Ghz L1 8kb. L2 512kb
GFX Card : NVidia 6600GT 128MB DDR3
RAM : 128MB DDR PC2100 (slot 1)
: 512MB DDR PC2300 (slot 2)
HDD : 80GB Western Digital IDE
OS : Windows XP Pro SP2

Edited by owenbear because: More info.
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Common cause for a Socket‑478 Pentium 4 swap that hangs at POST is missing firmware support for the new CPU rather than a simple voltage mismatch. Intel P4s use voltage‑ID pins and the motherboard’s voltage regulator will usually supply the requested core voltage; if the BIOS lacks the right microcode or support for that stepping/FSB combo the board can stop during POST. That makes a firmware update the first thing to consider.

Practical sequence to follow: keep the original processor installed while checking the current BIOS version in setup, then download the exact BIOS package for the P4B‑533VM from the maker and read the changelog/CPU support list. Use the manufacturer’s recommended flasher (EZ‑Flash or equivalent) from inside the BIOS when possible. Ensure a stable power source during the flash (UPS or at least a battery‑backed supply) — this reinforces ’s point. After flashing, clear CMOS and load optimized defaults before swapping CPUs.

Safe advice on an adhered CPU/heatsink: thermal pads or tape can grip strongly. A safer approach is to soften the adhesive (high‑purity isopropyl alcohol around the pad edges, or very gentle, controlled heat) and then twist the heatsink evenly — avoid metal prying and never apply force that could bend the PGA pins. After separation, inspect the CPU underside for bent pins and clean old thermal compound or pad residue before reseating.

Once the updated BIOS is in place and the new CPU installed, boot with minimal hardware (single RAM stick, no extras), check the BIOS report for CPU type and core voltage, then test stability. If problems persist despite a proper firmware update and correct seating, consider VRM/current‑capacity limits on the board or an unsupported CPU stepping; testing the CPU in a known‑compatible board is the definitive check. This builds on the points made by and while adding practical safety and verification steps.

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Member Avatar for owenbear

Hullo again,

After being given even more old PC bits I now have questions about switching CPU's.


I've tried swapping my old socket 478 1.7Ghz for a P4 2.5Ghz (socket 478).

The motherboard is an ASUS P4B-533VM.

And here begin the problems...(and the questions)!

1) After the swap the PC gets to BIOS then freezes, doesn't accept any keyboard input then restarts and repeats the above.

I've realised the P4 1.7 is 1.75 volts while the P4 2.5 is 1.5 volts (also the wattage is different). Is this the problem or should the motherboard adjust for this?

2) When I removed the heatsink from the 1.7 the CPU came with it and is stuck to the heatsink. Now I cannot reinstall it to it's 'home' motherboard. How can I get the CPU off the heatsink without damaging it. It looks like it's stuck using thermal tape or something. There is a black square around the edges of the CPU which I think is the tape.

3) Should this CPU work in this board anyway?

As always any help/information is greatly appreciated.

OwenBear

More info.

Mother board is: P4B-533VM socket 478
CPU (was) : P4 1.7Ghz L1 8kb. L2 256kb swapping to P4 2.5Ghz L1 8kb. L2 512kb
GFX Card : NVidia 6600GT 128MB DDR3
RAM : 128MB DDR PC2100 (slot 1)
: 512MB DDR PC2300 (slot 2)
HDD : 80GB Western Digital IDE
OS : Windows XP Pro SP2

From what I can find on Google the CPU swap 'should' work. On the Asus website it lists the motherboard as accepting both CPU's.
However, it says for the 2.5Ghz CPU it needs BIOS v1004 while with the 1.7hz CPU it says any.
Would I have to change the BIOS then?
And will I need to do this before changing the CPU's?
I've never changed the BIOS before so sorry if these are inane questions.

OwenBear

Member Avatar for crunchie

You need to put the original cpu back in, then download that BIOS version you listed and then flash the BIOS to the 1004 one.
Once done, exchange the cpu again and it should work.

Flashing the BIOS can turn your PC into a paperweight. Just saying.

Member Avatar for jak0b

Flashing the BIOS can turn your PC into a paperweight. Just saying.

ok - Worst case scenario. :)

I have flashed a couple hundred bios through the years, without any accidents.
The main thing to focus on, is to make certain that you have a stable power source for your pc, while it is flashing the bios.

Just don't pull the power from the computer, while the bios is being flashed.
And of cause, only use a bios which is intended for the specific motherboard model. (always get the new bios from manufacturer's homepage. -just for the record)

:)

edit:
also - follow the instructions on the screen, and think before you push buttons.
And if it seems to be stuck, leave it for 10 minutes (to let it finish). :)

Edited by jak0b because: n/a
Member Avatar for owenbear

OK thanks for the info guys - much appreciated.

I'm presuming since none of you said any different I will notice a speed increase IF I can get it to work.

@ crunchie - It's being a paperweight at the moment anyway so it's only gonna give me some experience in bulding PC's!

@ jac0b - Well your answer gives me a bit of hope anyhow! And I wil be patient!

A couple more questions....

Should I flash the 1004 BIOS? There are later BIOS's for this board - so would a later one work? Or should I just stick with the 1004?

P.S I got the P4 1.7 CPU off the heatsink by heating it up with a hairdrier (the CPU slid off once it was warm)!

Thanks again for your replies,

OwenBear.

Member Avatar for crunchie

Usually best to go for the latest version.

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