I've got maximum power dissipation of 3.7W for the AMD-133 and 4.29W for the Intel DX4-100 ... though unless the BIOS is aware of the AMD it might not set it up quite right and performance will be a wash.

BitWrangler wrote on 2026-04-27, 22:56:

I've got maximum power dissipation of 3.7W for the AMD-133 and 4.29W for the Intel DX4-100 ... though unless the BIOS is aware of the AMD it might not set it up quite right and performance will be a wash.

I think as this machine came out way before any DX4 (or i can imagine - AMD) was really official, i wouldn't think that the bios would support any quirks that came with the AMD at least... Perhaps best not to even try it 😀

my03 wrote on 2026-05-06, 16:16:

BitWrangler wrote on 2026-04-27, 22:56:

I've got maximum power dissipation of 3.7W for the AMD-133 and 4.29W for the Intel DX4-100 ... though unless the BIOS is aware of the AMD it might not set it up quite right and performance will be a wash.

I think as this machine came out way before any DX4 (or i can imagine - AMD) was really official, i wouldn't think that the bios would support any quirks that came with the AMD at least... Perhaps best not to even try it 😀

The BIOS doesn't control the speed of the Am5x86-133. The only potential problem is if the board is jumpered so that the Am5x86-133 is running in write-back mode, but the BIOS programs the chipset to expect it to be running in write-through mode. Jan Steunebrink has a period-correct webpage from when this upgrade was relevant to one's "daily driver" that talks about that issue http://www.steunebrink.info/amd5x86.htm

As long as the laptop supports 3.45V CPU's, there won't be any physical harm from trying an AM5x86 CPU.
The only risk would be power management crashes.

Although I can understand not wanting to buy a CPU that may not work. Not to mention the risk when pulling a 486 from a conventional socket.

the 'p75' can hit 160mhz so yes i'll take that over the iDX4. Some say the intel one was 'faster for quake' but that's been just hearsay at best from my experience (I lanned a AM5x86 @120mhz vs a iDX4/100 then, the amd shot nails faster).

leileilol wrote on 2026-05-07, 02:01:

the 'p75' can hit 160mhz so yes i'll take that over the iDX4. Some say the intel one was 'faster for quake' but that's been just hearsay at best from my experience (I lanned a AM5x86 @120mhz vs a iDX4/100 then, the amd shot nails faster).

40mhz fsb though?

Yeah it's a bonus when 486 laptop boards will do 33, you get a lot of them at 25

leileilol wrote on 2026-05-07, 02:01:

the 'p75' can hit 160mhz so yes i'll take that over the iDX4. Some say the intel one was 'faster for quake' but that's been just hearsay at best from my experience (I lanned a AM5x86 @120mhz vs a iDX4/100 then, the amd shot nails faster).

I used to own a DX4-100 back in the day and playing Quake, even 320x200 on it, was an unbearable experience and what prompted me to upgrade to a Pentium 133 in late 1996.

Neither the Intel 486DX4-100 or AMD 5x86-133 is really suitable for playing Quake due to the poor math co-processor performance.
You really need a Pentium class CPU for that.

However, if you have a Pentium Overdrive (P24T) 83 MHz CPU then it does make for an interesting Quake experience on a "486 class" system 😁.

jesolo wrote on 2026-05-07, 08:53:

However, if you have a Pentium Overdrive (P24T) 83 MHz CPU then it does make for an interesting Quake experience on a "486 class" system 😁.

In my personal experience, I had more trouble with Pentium Overdrive chips than what they were worth. Of course if you already have an Overdrive chip laying around then try it, but buying one is kind of a lottery depending on whether it works with the motherboard or not...

MagefromAntares wrote on 2026-05-07, 09:09:

jesolo wrote on 2026-05-07, 08:53:

However, if you have a Pentium Overdrive (P24T) 83 MHz CPU then it does make for an interesting Quake experience on a "486 class" system 😁.

In my personal experience, I had more trouble with Pentium Overdrive chips than what they were worth. Of course if you already have an Overdrive chip laying around then try it, but buying one is kind of a lottery depending on whether it works with the motherboard or not...

Fortunately, I was lucky with my 83 MHz version.
I do agree you need a fairly "newer" 486 motherboard (preferably a Socket 3) to ensure proper compatibility.

From an integer performance perspective, it does perform more or less on par with that of a Pentium 75 MHz CPU and similarly with its floating point performance.

However, an AMD 5x86-133 and Cyrix 5x86 will give you better integer performance if you apply some "tweaks" to the CPU (either via overclocking for the former or some registry tweaks for the latter).

But, I digress a bit.

Hey guys,

thank you all for you very good input. Then i know i might not have to worry too much about the bios itself and that it could well be worth a try 😀 I'll probably try it shortly (and ping back here).

I "did" actually get a P75 overdrive for it. Unfortunately, the fins on this cpu was too tall for my laptops taste (couldn't snap it shut with it installed). This particular machine has this rectangular cooler that extends from the cpu all the way to mounting points at the back, and even with that removed (relying on the P75 fins for cooling) it was too high.

At some point i was considering trying to remove the heatsink from the CPU, but that seemed to be a lot of work (if even possible, reading about how glued on they might be). I might have some easier roads ahead by simply trying the AMD 133 😀

br

Well, the AMD cpu arrived and i tried it out. It actually will start the boot process, counting the memory, etc. Can even enter the bios on the machine, but when it is time to actually load DOS, it just hangs. Before this, it describes the CPU as a 100mhz variant (i have the bus set to 33 and dx4 option enabled.

Unless there are any other tricks to try out, i assume this cpu is not compatible with this laptop (?)

From my experience the 486 and 5x86 is about the same. Neither can play MP3, Video, or Win95 games well.
Or run office 97 well’

You really need a Pentium class cpu.
The Pentium 133 and Pentium 200mmx were very popular CPU back in 1990’s
These cpus ran dos and windows-95 software well and played games well too.

You will notice the difference right away from the 5x86 to the Pentium cpu.

Office 97 isn't that bad on 66mhz up as long as you have 16MB or more of RAM, just have to be careful not to install absolutely every feature on the disk, prune it to stuff you use more than 5% of the time. It's actually probably more responsive than modern office on a $299 walmart laptop.