Not sure I understand you question.
It is logically and physically a part of the motherboard. Packard bell probably cheaped out and decided not to solder it.
This made 3.3v jumpers (J32) non-functional.

By soldering missing parts you will make this jumper functional and will be able to use 3.3v CPUs
I plan to do this and will update this thread with results.
I still need to find a DX4 chip though (for cheap)

Thanks for the clarification.

ahtoh wrote:

I still need to find a DX4 chip though (for cheap)

Is it a DX4 with L1 WT (not WB)? I suppose the mainboard doesn't have necessary features to support L1 WB CPUs.

ahtoh wrote:

The only problem is to get proper isolation because the case of the chip is connected to the output, and the pad on the board is connected to the ground. So it will require some isolator and a bolt to get proper heat dissipation.

I haven't found any 3.3v or adjustable LDO in TO-220F package (plastic package that doesn't need an additional insulator). Maybe the manufacture of the mainboard supposed to use just insulator for TO-220, somethink like this (to-220 insulator kit). You can find it in an (bad/not working) AT or ATX power supply.

Good start. I'm planning on looking inside a cheap ATX PSU that's sort of working, or another PSU that hasn't seen power in years.

Just bought two Intel dx4-100 chips - one with WB cache and another with WT.
I believe both will work just fine. I tested the board with both WB and WT versions of dx2-66
Is there a benchmark where the difference between WB and WT is noticeable?
I'm also not sure if WB mode should be specifically enabled in the BIOS, PB450 has no such a setting.

The PB450 motherboard complains about the Pentium OverDrive 63 and/or 83 units as the write-back cache has a bug in them. I'd say try the WB version of the DX4-100 and see how it performs.

Also, good luck.

How's it going with the project?

I've just moved to another state, was quite busy so no news yet. will update as soon as I get to this.

It works

Excellent 😀

Is that a fixed voltage regulator or an adjustable one? It's not really clear which from the pictures but I assume it's the LT1085CT-3.3 since the R131 is just bridged?

I bought an adjustable one but haven't fitted it because I haven't put time into working out which resistor would be needed there.

I bought the fixed one just because it was cheaper.
For adjustable you will need 120 ohms and 200 ohms resistors.
Check the formula in the datasheet.
It is also important to solder two tantalum capacitors C206, C207

WB version of the DX4-100 also works but I didn't notice any performance difference between WB abd WT
Actually, the performance is quite not where I expect it to be, maybe because of missing L2 cache

Ok I did more tests on another motherboard. Looks like WB chip will only work in WB mode on some board revisions only.

Here are some benchmark results with WT and WB chips and 512K L2 cache:

ahtoh wrote:

I bought the fixed one just because it was cheaper. For adjustable you will need 120 ohms and 200 ohms resistors. Check the form […]
Show full quote

I bought the fixed one just because it was cheaper.
For adjustable you will need 120 ohms and 200 ohms resistors.
Check the formula in the datasheet.
It is also important to solder two tantalum capacitors C206, C207

Which ratings did you get for the capacitors and they are important for the fixed voltage, right?

I used a couple of 22uF
The datasheet says 22uF is recommended

Is there a specific voltage for the capacitors? Also, how'd you get the L2 cache to work? I can never get the 128KB L2 cache to work correctly (possibly because I have an AT&T 64Kx1 chip instead of Cypress. Which cache chips are you using? Also, excellent project, and is it necessary to bridge R131 together for the voltage regulator? I'm planning on doing this sometime soon.

The capacitors should be rated above 3.3v.
The cache chips I'm using are on page 5 in this thread.
You have to bridge R131 if you're using fixed version of the LDO (LT1085CT-3.3) otherwise you'll need two resistors mentioned above.

Are these the correct items in question (minus the 16v 10uF SMD electrolytic capacitors since my VooDoo2 card isn't working properly)?

Or

Also, what length are the caps from one end to the other? Is it 1mm or less? Thanks, man. I also love the project.

0603 is definitely too small
0805 may fit, but not sure, must be tantalum, not ceramic
mine are around 3.4x2.8mm size
also buy a 0-ohm smd resistor so your bridge look nice and professional and not like mine 😀

ahtoh wrote:

0603 is definitely too small 0805 may fit, but not sure, must be tantalum, not ceramic mine are around 3.4x2.8mm size also buy a […]
Show full quote

0603 is definitely too small
0805 may fit, but not sure, must be tantalum, not ceramic
mine are around 3.4x2.8mm size
also buy a 0-ohm smd resistor so your bridge look nice and professional and not like mine 😀

I saw this: 6.3V 22uF 1411 (3528 Metric), 1210 and 10V 22uF 1411 (3528 Metric), 1210

However, the package/size says: 1411 (3528 Metric), 1210 and the dimensions are 3.5mmx2.8mm (.1mm longer than yours). Would either work?

...Or these CAP TANT 22UF 6.3V 20% 1206 and CAP TANT 22UF 10V 10% 1206?