The board still works in my P4 system with the regulator off

And in my Socket 7 (5V) system with the regulator enabled (note the green light)!

Good work!

Good job!

mbarszcz wrote on 2023-08-04, 02:34:

I took the 5V from before the polyfuse that carries 5V to pin 9 of the VGA port, and fed it back into the unpopulated capacitor pads at the bottom of the board. I added a small switch on the top of the board that would ground the enable pin so the regulator could be easily switched off. There is also a light on the module that shows when it is running, so there is visual confirmation with a green LED.

So, the green wire is for buck converter on-off switch (output?) to ground, the black wire is for ground input, the "lower" red wire is 5V input voltage and the "upper" red wire must be 3.3V regulated output - is this correct? This is the essential part of the mod and it will be nice if you explain what pads on the videocard's PCB was used.

Edit: I think I figured it out on the second reading

3.3 volts are available elsewhere on the motherboard. find a coil from 3.3v and run a wire from it to the correct pin on the PCI slot.

analog_programmer wrote on 2023-08-04, 05:39:

Good job! […]
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Good job!

mbarszcz wrote on 2023-08-04, 02:34:

I took the 5V from before the polyfuse that carries 5V to pin 9 of the VGA port, and fed it back into the unpopulated capacitor pads at the bottom of the board. I added a small switch on the top of the board that would ground the enable pin so the regulator could be easily switched off. There is also a light on the module that shows when it is running, so there is visual confirmation with a green LED.

So, the green wire is for buck converter on-off switch (output?) to ground, the black wire is for ground input, the "lower" red wire is 5V input voltage and the "upper" red wire must be 3.3V regulated output - is this correct? This is the essential part of the mod and it will be nice if you explain what pads on the videocard's PCB was used.

Edit: I think I figured it out on the second reading

Sorry for the confusion, when you ground the green wire through the switch (output enable), it disables the buck converter.

Here's a labeled picture:

ala_borbe wrote on 2023-08-04, 09:24:

3.3 volts are available elsewhere on the motherboard. find a coil from 3.3v and run a wire from it to the correct pin on the PCI slot.

mbarszcz wrote on 2023-08-04, 02:34:

I didn't want to modify the board or have a bunch of wires hanging all over the case to power the GPU externally, and wanted to keep the mods on the card.

mbarszcz wrote on 2023-08-04, 15:49:

Sorry for the confusion, when you ground the green wire through the switch (output enable), it disables the buck converter.

Yes, I have swapped the purpose of the two red wires, because again I did not read carefully that

mbarszcz wrote on 2023-08-04, 02:34:

I took the 5V from before the polyfuse that carries 5V to pin 9 of the VGA port

But from the picture with the explanations, it's all clear now. Thanks!

Many motherboards lacking 3.3v don’t even route those pins to other slots.

There are actually two group sets of pins with 3.3v on the pci specification

Some were 5v on older gen mobo slots but later those pins changed to 3.3v which sounds like a nightmare but in practice hasn’t been a road block. For the final version of the 3.3v adapter we just ignored them. And let the motherboard do what it wanted with them.

See all you have to do really is feed power to the pins that only ever were marked as 3.3v on the motherboard and vola! 3.3v compatible pci slot.

On your card, backfeeding or parallelling the mobo/psu 3.3v or to other cards would’t likely be an issue as the voltage would be the same, the only ussue would be if the system didn’t have 3.3v, and DID route signal and other cards were drawing too much from the mod you did. (Over load it with too much draw) this could likely be solved by using a beefier mod power supply. See there was once such a thing as a 3.3v pci power supply card. It took I believe 5v and backfeed 3.3 back to the motherboard as the motherboard lacked the converter. Some of these systems actually used this to run the processor/s

It is worth noting that many gfx cards are very picky with socket 7 and 3.3v isn’t always the problem or only problem. I would say you got lucky here that it was the only incompatibility. Don’t take that wrong though, not saying trying cards is dangerous, just that there are a heck of a lot of ones that won’t post properly 🤣.

So having the mod on in your p4 system shouldn’t cause a problem. At least not one that I am aware of. It would basically be the same as if the card had come populated with the converter. If wired correctly it should be sending 3.3v to pins that would or already do have 3.3v anyway. So there is no conflict if potential is the same.

You could get into concerns of line noise or power supply quality. But chances are that isn’t going to be a problem, and it’s all speculation without a scope. Chances are that your power supply will be just fine for what you are trying to do. It may even be better than the supply that the card would have been populated with.

If you wanted to add a smoothing cap, you would hook up the circuit to a scope and analyze the interference frequencies and size a capacitor that responds best to each frequency

My go to for socket 7 is radeon 7000-9xx0 I see the most of those working of any cards I have. Anything newer isn’t going to work because of pci spec/bios/ or drivers.

On a system like yours you could probably get 800-900 3dm2000 with a 7500

Curious what you are getting with that card. Could you share? 😀

Here's some benchmarks for you:

Sphere478 wrote on 2023-08-04, 17:27:

Many motherboards lacking 3.3v don’t even route those pins to other slots. […]
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Many motherboards lacking 3.3v don’t even route those pins to other slots.

My go to for socket 7 is radeon 7000-9xx0 I see the most of those working of any cards I have. Anything newer isn’t going to work because of pci spec/bios/ or drivers.

On a system like yours you could probably get 800-900 3dm2000 with a 7500

Curious what you are getting with that card. Could you share? 😀

TNT2M64 / Pentium MMX 233MHz / Win98

Here's the same card on the Pentium 4 system removing the CPU bottleneck
TNT2M64 / Pentium 4 2.53GHz / WinXP

3DMark 2000 Results Comparison

Certainly not the most impressive performance under Windows, although that was never really the intention with my Socket 7 233MHz Machine. If it will run under Windows on a 233MHz, it will likely run better under Windows on a PIII with much more CPU power.

However, the DOS performance and compatibility on the TNT2 M64 is quite good. In most cases, there is a performance boost over the S3 Trio 64V2/DX.

1+-----------------------------------------+------------+------------+--------------+
2|                               Benchmark | S3 64V2/DX |   TNT2 M64 | % Difference |
3+-----------------------------------------+------------+------------+--------------+
4|                    Speedsys VESA Memory |    2048 KB |       16MB |         800% |
5|              Speedsys VESA Memory Speed | 22337 KB/s | 73849 KB/s |         331% |
6|            2) 3DBench 1.0c (Faster PCs) |      165.5 |      176.6 |         107% |
7|           3) Chris's 3D Benchmark (fps) |      155.6 |      275.2 |         177% |
8|   4) Chris's 3D Benchmark 640x480 (fps) |       44.3 |       80.6 |         182% |
9|  5) PC Player Benchmark (320x240) (fps) |       58.1 |       58.8 |         101% |
10|          6) PC Player Benchmark 640x480 |       23.0 |       24.4 |         106% |
11|  a) Doom min details (Slower PCs) - fps |      308.6 |      321.9 |         104% |
12| b) Doom max. details (Faster PCs) - fps |       84.1 |       95.0 |         113% |
13|                 c) quake timedemo - fps |       52.0 |       53.0 |         102% |
14|               d) Quake timedemo 360x480 |       22.0 |       23.8 |         108% |
15+-----------------------------------------+------------+------------+--------------+

mbarszcz wrote on 2023-08-05, 05:52:

Certainly not the most impressive performance under Windows, although that was never really the intention with my Socket 7 233MH […]
Show full quote

Certainly not the most impressive performance under Windows, although that was never really the intention with my Socket 7 233MHz Machine. If it will run under Windows on a 233MHz, it will likely run better under Windows on a PIII with much more CPU power.

However, the DOS performance and compatibility on the TNT2 M64 is quite good. In most cases, there is a performance boost over the S3 Trio 64V2/DX.

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1+-----------------------------------------+------------+------------+--------------+
2|                               Benchmark | S3 64V2/DX |   TNT2 M64 | % Difference |
3+-----------------------------------------+------------+------------+--------------+
4|                    Speedsys VESA Memory |    2048 KB |       16MB |         800% |
5|              Speedsys VESA Memory Speed | 22337 KB/s | 73849 KB/s |         331% |
6|            2) 3DBench 1.0c (Faster PCs) |      165.5 |      176.6 |         107% |
7|           3) Chris's 3D Benchmark (fps) |      155.6 |      275.2 |         177% |
8|   4) Chris's 3D Benchmark 640x480 (fps) |       44.3 |       80.6 |         182% |
9|  5) PC Player Benchmark (320x240) (fps) |       58.1 |       58.8 |         101% |
10|          6) PC Player Benchmark 640x480 |       23.0 |       24.4 |         106% |
11|  a) Doom min details (Slower PCs) - fps |      308.6 |      321.9 |         104% |
12| b) Doom max. details (Faster PCs) - fps |       84.1 |       95.0 |         113% |
13|                 c) quake timedemo - fps |       52.0 |       53.0 |         102% |
14|               d) Quake timedemo 360x480 |       22.0 |       23.8 |         108% |
15+-----------------------------------------+------------+------------+--------------+

The biggest upgrade in this case is replacing old videocard (2D pre-Virge "3D deccelerator"model) with some decent for its time 3D accelerator videocard.

You have done nothing wrong with this mod. You will not put more PCI videocards demanding missing 3.3V PCI line in this mobo, thus overloading the buck converter. And the modification of this cheap videocard is not permanent. A way better solution than mangling the motherboard.

It is interesting how much better that card does on the p4

Reason I say this is with a different card I can get like 400 more points in 3dm2000 on basically the same pmmx 233 system. So a faster card still will help. But your slower card will beat my faster card on a faster system.

I’m sure driver overhead is at play here but I have a hard time believing your old geforce driver is more demanding than a newer radeon 9k driver. Though idk for sure. But it all does seem to suggest the card its self being faster does have a few punches left to throw into the fight. “Bottlenecks” I hate the term as it lacks any nuance. Yet again prove to be more gradients than brick walls.

Facinating.

Pentium MMX 233 aiming for the stars!

Great work OP! I have a FX5500 card here with the same issue on my Socket 7 motherboard so I might attempt something similar one day.

An aside on the M64 - the VESA support is great but there are situations when UniVBE comes in handy. UniVBE won't see a M64 but this handy patch came out recently to fix that problem: NVPatch - making UniVBE work on NVidia cards

Sphere478 wrote on 2023-08-05, 08:11:

It is interesting how much better that card does on the p4

My guess is that because this card is pre-TnL (pre-GeForce), it relies heavily on the CPU for certain operations which are simply "faster" due to the raw horsepower behind the P4 compared to the Pentium 233. There may also be SSE optimizations from Coppermine optimizations, depending on which driver was used.

I've read that this can be a problem with the Voodoo 2 on fast CPUs causing the chips to overheat, since they had never been tested on such hardware since it didn't exist.

I have this PCI video card, just a different model, I wanted to ask if you have already adapted this video card?

It simply doesn't show an image on my motherboard model M748LMRT 1.3A, I've already made different settings in the BIOS and nothing shows an image, I've already updated the BIOS and it doesn't show any signs of life, the video card works on another more current computer, only Not on this motherboard.