If you're running a P3-650, that's a Coppermine chip, so a 700 should be similar enough that it works. Keep in mind that, especially for faster processors, it might be cheaper to get a slotket and s370 cpu than a Slot 1 cpu. I wouldn't upgrade to 700MHz, but try to get something in the 1GHz range.

I have a similar Compaq motherboard, but smaller, and I was able to use a slotket and pre-modded Tualatin 1400 with it (at 1050MHz due to the 100MHz FSB). So your motherboard probably isn't a limiting factor, but what you can find are are willing to spend is.

P3-650 > 700 is a tiny upgrade. You might get a few FPS, but I'd doubt that if it doesn't play well at 650MHz, it will magically become a good experience at 700MHz. In general, the lowest specified CPU will still give a poor experience.

That 041Ch board seems to be a pretty standard i440BX thing, so as far as chipset is concerned, everything with 100MHz FSB up to 1100MHz could work (or Celeron 1400, if Tualatin voltages are supported, which they probably aren't). Question is what the Compaq OEM BIOS will let boot. I have a Compaq AP550 board from similar era that is immensely picky about CPUs - it refuses to boot with anything with a different S-Spec to the CPUs originally supplied with the system. So YMMV given Oetker's experience. I'd try to find concrete examples of someone running the CPU you are considering on your 041Ch board before shelling out on it.

MrYossarian wrote on 2022-07-11, 00:57:

Hi there, so I was wondering, is it possible to replace the in-board Pentium III 650 MHz with one that's 700 MHz? […]
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Hi there, so I was wondering, is it possible to replace the in-board Pentium III 650 MHz with one that's 700 MHz?

Some games that I'd like to play, like AVP2, say that they work better with a P3 700 MHz, but, I don't want to order one if it's not gonna work on that computer. The board is a Compaq 041Ch if that can help.

So, should I order one or is it impossible? Or better yet, will it make much a difference to have a P3 650 MHz vs 700 MHz?

Thanks in advance.

a 700 mhz cpu isn't much more and they give recommended specs over bare minimum taking into account period correct systems can be poultry you might already have a faster hard disk or more ram for example that wasn't in the machine factory. However, if you find it doesn't work (it should) you need a microcode update in your system bios obtainable by the method of bios modding; i recommend for the 833mhz and faster cpu's if they come up as the wrong speed in post under slotket configuration (it posts but says its a 833mhz not 1,000mhz).
A slotket 833mhz 850mhz I would go for if cheaper than a 700mhz module I'm sure people will help with slotket bugs.
Chipset specifications would tell how fast it can go too but fastest isn't always the best faster it goes more power to run can make the proprietary design PSU to strain and they aren't as common as the standard design module so personally i wouldn't push more than 850mhz without a power supply upgrade.
So my final words are appart from hard disk and ram i'd stick to what I have really.
I wonder if a faster GPU would be cheaper in this scenario

dionb wrote on 2022-07-11, 10:09:

P3-650 > 700 is a tiny upgrade. You might get a few FPS, but I'd doubt that if it doesn't play well at 650MHz, it will magically become a good experience at 700MHz. In general, the lowest specified CPU will still give a poor experience.

That 041Ch board seems to be a pretty standard i440BX thing, so as far as chipset is concerned, everything with 100MHz FSB up to 1100MHz could work (or Celeron 1400, if Tualatin voltages are supported, which they probably aren't). Question is what the Compaq OEM BIOS will let boot. I have a Compaq AP550 board from similar era that is immensely picky about CPUs - it refuses to boot with anything with a different S-Spec to the CPUs originally supplied with the system. So YMMV given Oetker's experience. I'd try to find concrete examples of someone running the CPU you are considering on your 041Ch board before shelling out on it.

Interesting that there's such a difference between Compaq boards...

A board that supports Coppermines should support Tualatin voltages though, although it's always best to check the VRM data sheet. Coppermine VRMs go low enough, but not in small enough increments, so the chip would be ever so slightly over or undervolted, I don't remember which.

If its the same as my 041CH board then I've recently tested mine running a socket 370 / slocket combo to 1GHz ( SL5QV 1000/256/100). Voltages shouldn't be a problem if (again like mine pictured) it's fitted with the Cherry / ONSemi CS5159 which can handle both coppermine & tualatin requirements.

Thank you all for the replies.
I went ahead and bought a 700 MHz processor, it will train me to change the processor of an old PC at the same time. I do understand that it probably won't make much of a difference, kinda like how my GeForce 2 Pro 64 MB that's an AGP 4x is running at 2X on this motherboard. Apparently, it doesn't make much of a difference, hopefully it's the same thing here with the CPU. I can just return the processor if it doesn't work I guess.

@Oetker
Admitedly, I have no idea if the motherboard has a socklet since I never changed the CPU.

@dionb
That's what I was worried about, this motherboard came with this computer, a Compaq EP650, the 650 gives me a pretty good idea that it might be locked to a 650, but, we'll see how it goes when I'll try to replace it.

@zapbuzz
I have never really done BIOS modding before, how would that work? Is it like where you just have to put the upgrade in a floppy drive and do the update? If so, is there a place that have a list of modded BIOSes?

I will let you guys know how that goes when I'll get the CPU.

Oetker wrote on 2022-07-11, 12:45:

[...]

Interesting that there's such a difference between Compaq boards...

A board that supports Coppermines should support Tualatin voltages though, although it's always best to check the VRM data sheet. Coppermine VRMs go low enough, but not in small enough increments, so the chip would be ever so slightly over or undervolted, I don't remember which.

The difference might be due to workstation (it's a dual Sl1 i840 monster) vs desktop. Or just that the BIOS engineer had a bad day. Even CPUs of same stepping didn't work; P3-866 slot 1 c0 stepping worked fine, P3-800 So370 c0 stepping didn't boot. Only difference to BIOS is S-spec. Used several slockets (including an upgradeware Slot-T and an MSI MS-6905 v2 ) that work on every other Slot 1 board I own. Still, was able to find a second identical P3-866. Just need to bodge a fitting cooler as the sockets are spaced too closely for a regular one...

MrYossarian wrote on 2022-07-11, 13:44:

Thank you all for the replies.
I went ahead and bought a 700 MHz processor, it will train me to change the processor of an old PC at the same time. I do understand that it probably won't make much of a difference, kinda like how my GeForce 2 Pro 64 MB that's an AGP 4x is running at 2X on this motherboard. Apparently, it doesn't make much of a difference, hopefully it's the same thing here with the CPU. I can just return the processor if it doesn't work I guess.

Almost exactly different to the GF2 -that theoretically won't run at full potential, but in fact will, as the bottleneck's not the AGP bandwidth but internal bandwidth on card between GPU and RAM, and it will run one hell of a lot faster than any AGP 2x alternative. On the other hand, the P3-700 will run at full potential, but won't actually significantly improve anything. Except your Slot 1 CPU swapping skills, hopefully.

[...]
@dionb
That's what I was worried about, this motherboard came with this computer, a Compaq EP650, the 650 gives me a pretty good idea that it might be locked to a 650, but, we'll see how it goes when I'll try to replace it.

Pure coincidence. The AP550 came with 133MHz FSB Coppermine CPUs at over 600MHZ, and there were other systems/boards with similar numbers around that time unrelated to exact CPU speed. The Deskpro 2000 shipped with a Pentium 133 originally 😉

dionb wrote on 2022-07-11, 21:11:

Or just that the BIOS engineer had a bad day. Even CPUs of same stepping didn't work; P3-866 slot 1 c0 stepping worked fine, P3-800 So370 c0 stepping didn't boot.

I suspect not and the reason that the Socket 370 PPGA did not work is that the BIOS only has the Slot 1 SECC2 CPU µCode.

Below you should note that there is different CPU µCode for the different socket types in the Windows XP update.sys so it's possible the BIOS does not have them all.

What BIOS version do you have?

red-ray wrote on 2022-07-12, 08:02:

[...]

I suspect not and the reason that the Socket 370 PPGA did not work is that the BIOS only has the Slot 1 SECC2 CPU µCode.

Below you should note that there is different CPU µCode for the different socket types in the Windows XP update.sys so it's possible the BIOS does not have them all.

Looks highly plausible - and given that both ucodes have same date so would have been available, I'd say "engineer had a bad day" still covers it.

What BIOS version do you have?

Would need to get digging - haven't done much with this build recently due to lack of time, specifically to get it into a decent case (PSU doesn't fit into most ATX cases...) and to get a good solution for the second CPU heatsink.

dionb wrote on 2022-07-12, 08:32:

I'd say "engineer had a bad day" still covers it.

I suspect not, the BIOS can only be 512KB in size and my guess is they they ran out of space. SIV scans the BIOS for CPU µCode and did not find any on my AP550 which is often down to it being compressed to reduce it's size.

OK about the case issue, I had the same problem and in the end left the case cover off!

I have SIV save files for all my systems so it's easy for me to check the BIOS version and I tend to forget others often need to boot their systems.

So, quick update, I have finally received the Pentium III 700 MHz processor and I replaced it.

Had a little bit of trouble replacing the former processor because it has an heatsink that is specifically made made for the motherboard, that way it can be firmly seated, which isn't the case of the 700 MHz processor I got.

Former processor:

New processor:

So, not only is the heatsink of the newer processor smaller, but, it also couldn't fit. I couldn't remove the heatsink because I am pretty sure the heatsink is kinda like soldered? I have seen a few videos of people removing the heatsink of these processors, but they were black instead of silver and they didn't have the pins that you have to pull in order to detach the heatsink from the processor. So eventually, I removed this thing, I'm not really sure what to call it, but, it secured the processor. Don't worry, I've kept the other one in.

To my surprise, it worked, so I'm pretty happy about it. Thank you all for your thoughts and for your help with this!