Can't answer for Intel but I ran an Am486DX4-100 for a few months at 5V.
Only reason was that my motherboard was 5V only and wouldn't work with an Intel DX4 Overdrive, or a Pentium Overdrive. It worked fine with the AMD DX4, which has only 8KB cache compared to the 16kb of the Intel DX4.
I believe the chipset or BIOS just didn't like the extra cache.

Anyway, I had a heatsink and fan on it, and it didn't really get that hot, and I never noticed any problems. I've since swapped the motherboard to one that works with a DX4 overdrive.

I think the later AMD units are known for having a 5 V tolerance. As I have a somewhat rarer Intel DX4 w/WB cache, I don't want to stess it out at 5 V for Windows tests unless someone here has had some long-term experience with Intel DX4's at 5 V. I'd really like to add the Intel DX4-133 to the U4BC, but don't want to fry it in the process.

Btw, the DOS results for the Intel DX4-133 are quite good. It breaks the double digit barrier in Pcpbench,

Pcpbench = 10.3 [VESA Modus 100, 640x400 8bpp LFB].
Doom1 timedemo 3 = 60.2 fps
Quake1 timedemo 1 = 16.5 fps
3Dbench = 90.0

FWIW the AmDX4 I was using said 3 VOLT on top and made no mention of 5 volts. From what I can find on the internet it appears some AmDX2's were 3.3V/5V tolerant but there's nothing to suggest the DX4's were. but since I've never tried a non-overdrive Intel DX4 at 5V for any real length of time I can't really provide a real answer.

SpeedSys results for the Intel DX4-133. It falls in somewhere between an AMD X5-133 and an AMD X5-160.

You should try watercooling it. 🤣

If it can be run at 150 MHz, then some alternative to fan cooling might be worth it, but at 133 MHz, an AMD X5-160 is already faster.

Here's an interesting question, is the Intel DX4-100 w/WB cache considered a P24C or a P24D?

The Intel DX4-100 w/ WT cache is often called a P24C, while the Intel DX2-66 w/WB cache is often called a P24D. So what is the DX4-100-WB called?

feipoa wrote:

If it can be run at 150 MHz, then some alternative to fan cooling might be worth it, but at 133 MHz, an AMD X5-160 is already faster.

Here's an interesting question, is the Intel DX4-100 w/WB cache considered a P24C or a P24D?

The Intel DX4-100 w/ WT cache is often called a P24C, while the Intel DX2-66 w/WB cache is often called a P24D. So what is the DX4-100-WB called?

Do you have a part number for the WB version? That might help in finding more info.

sliderider wrote:

Do you have a part number for the WB version? That might help in finding more info.

The CPUID for the WB version is noted in the U4BC and is SK096.