Lapping the Geforce 2MX - spodesabode.com archive

Here I am sitting with an Abit Siluro GF2MX graphics card. I'm doing fine with it until the day that my bro decides he's gonna play a bit of social engineering. Somehow he cons my father into swapping his funky GF2GTS for my bro's old TNT2. A hand-me-down from my old system at that! Scary thing is, my father still thinks his TNT2 is faster for Age of Empires II.

Now I'm the one who's behind in speed, and whilst I know there's not much catching up I can do, I know I can do better. I break out the overclocking tools, and soon discover my little Siluro isn't going to overclock very far. This just isn't good enough, so I rip the Siluro out of my machine.

See that funky fan? Ok, Abit are cool, they put a nice fan on the heat sink. You can't really see it from the photo, but the heat sink is something else. It's about 3mm thick, and looks like it'd struggle to cool a 486. Not only that, but there's no thermal compound under the heatsink. Wonder if this might be my problem?

Now, this looks more like a heatsink. I managed to dig an old heatsink out of my junk cabinet. It should do just a little bit better than the hotplate Abit included! Notice it's still got the 75Mhz sticker on the side. No prizes for guessing what machine this was off.

I start by removing the HSF unit from the GF2MX. It was surprisingly easy to remove, just two plastic clips holding it on. No epoxy, no goop underneith, no leaving the card in the freezer. I'm disappointed. Hey, look, it's a nekkid Geforce 2MX! Wonder if anyone would pay to look at nekkid chips?

I grab the straightest edge I can find (a copper sheet), and put it across the top of the GF2MX chip. Looking, I can see light. Looking carefully, I can see that the chip surface is most definately concave. That's not going to help me overclock it at all! I decided that seeing as I've got this far, I'll lap the top of the chip. I grab my sandpaper (I'm in the middle of decorating at the moment!), and find a handy sheet of glass. Then I find a problem. If you look carefully at the picture of the card, you can see the small problem. There's components mounted on the board on two of the sides that'll foul any attempt at lapping. I'm not foolhardy enough to try and lap capacitors, fan connectors and crystals as well as my GPU. In a fit of madness, I decide that anything that's in the way is going to come off the board. Yup, it's soldering iron time!

This is before I threatened it with a soldering iron.

It didn't co-operate, so this is what happened to the board.

I started lapping the GF2MX, and then discovered that it's hard work lapping whatever material the packaging is made of. Not only that, but I discovered that some of the surface mount capacitors on the board were too tall and were beginning to wear down! Out comes the soldering iron again, and the four offending capacitors are removed. Plenty more sanding later, and the GF2MX is looking more like it. Don't underestimate the work needed on a chip that's as concave as my GF2MX was! It's a lot of work.

Having worn out all my sandpaper, going through the grades to get a reasonable finish, the GF2MX ends up looking like this! I had fun doing the same thing to my P75 heatsink. The heatsink was flatter however. The next problem was trying to fit the heatsink on the board. Although the heatsink covered the mounting holes, modifications were needed to the heatsink to allow it to mount. Grabbing my trusty Minicraft, I shaved off 5 of the pins on the heatsink, and then sanded down the top so I could get the two plastic pins back through.

Next step was to solder all the components I'd removed earlier back onto the board. Next up comes the Artic Silver.

Finally, I put the two pins that held the original HSF on through the new heatsink, and clipped it into place. The new HSF was slightly thicker, and required a lot more pressure to attach it to the board. Eventually I got the HSF attached, and the fan plugged back in again. Will the board ever work again?

Plugging the board back in again, I held my breath as I hit the power switch. Hey, at least the machine powered up! The GF2MX still recognised all 32Mb of memory, and all was well. I let Windows load up, and everything held together. Not wanting to stress the card just yet, I hit the net to check out what's new on Spode's forums. The machine promply locked up. No smoke, no bangs, just a lock up, so I reboot the machine. This time around, the GF2MX claims there's only 16Mb on board. I let Windows boot, and examine the NVidia extensions

I never knew that a 16Mb Geforce card was possible! I ran 3DMark2000, and the card ran it fine. In fact, the card ran perfectly, despite only seeing half it's memory. I removed the card and examined it carefully. I changed the HSF mounting to use Dr SurlyJoe's favoured method, screws with springs to apply pressure. I also found a fine sliver of aluminium bridging two of the pins on one of the RAM chips - Ooops! Putting the card back in the machine, it recognised all 32Mb of memory.

I finally got the card up and working, and started work on overclocking it. Using the scientific method of applying a finger to the back of the card, it appeared to be running cooler. I managed to get 200Mhz out of the core, up 10Mhz from the 190Mhz it managed previously. Not a great improvement, but it did allow me to get a 3DMark2000 score of 5220, up from 5125.

Aidan II

Note From Spode: Aidan has gone to the real extreme with unsoldering all components and this should be attempted only by the most competent solderman.