1. Design
The adapter boards have castellated holes to solder to the EDO RAM chip footprints on the main board. The female pin header is a 2x20 1.27mm pitched double-row SMD one. I made a cutout for the pin header to be mounted from the bottom of the board. This is to adapt to a more appropriate height, as well as making sure the adapter can't be easily ripped off of the adapter board when installing & removing RAM modules.
The RAM modules are tiny 4-layer PCBs with one EDO RAM chip on each side. The male pin header is a double-row 1.27mm-pitched one. You will need to build a total of eight RAM modules to complete the 8MB build.
This project is created with cost and availability in mind. Both pin headers are very common and cheap. The PCBs are relatively cheap to order. The EDO RAM chips are consistently in stock on eBay.
Please be reminded that extra RAM does not bring any significant performance gain to the Voodoo 1 in most use cases. This is a pure functionality expansion, and the performance in that expanded scenario is miserable. There are very good reasons why 3Dfx ended up going with the 2+2 RAM configuration instead of more.
BitsUndBolts made a video benchmarking the cards before and after the RAM expansion.
To complete this mod you will be soldering the following number of joints:
- FBI & TMU Board (2x)
- Castellated Holes: (40-4)*4
- SMD Headers: 40*4
- SMD Resistors:2*2
- RAM Modules (8x)
- J-pins: 40*2
- Pin Headers: 40
- Main Chip Jumpers
- Tiny Bodge Wires: 3
- PCB Pads: 3
Total: 1582 (I made about 3 mistakes in my personal attempt)
You may not gain any extra performance out of this mod, but you will get a lot of practice soldering various types of joints!🤡