Ok so here's a short tutorial on how to make custom SLI cables.
Patience and some soldering skills required
1) Get two SLI cables that are the same colour
2) Align then so the connector edges are facing the same way
3) Chop off the matching connector. Start with the corner and keep making your way around.
4) Eventually the plastic connector will pop off. Cut off the remaining contacts. Repeat this for the other cable and the matching connector from point (2)
5) Make sure to put on a large piece of heat shrink on one of the connectors and set it aside (We'll call this connector "studded" - i'll explain later)
6) Next cut a smaller piece of heat shrink and set it aside for later (this will be for the "non-studded" connector)
7) If you haven't done so already, prepare the "non-studded" cable by removing the plastic connector as outlined in points 3 - 4.
8) To prepare the non studded connector you will now need to desolder all the remains of the pins. To do this, use a fairly fine tip soldering iron and tweezers. Press the soldering iron against the pin, trapping it between the tip of the soldering iron and the tweezers and pull up. Repeat this 26 times
This is a photo of 1 pin removed. Pin is on the table.
This is a photo of all the pins removed. Pins on the table
9) Put a bit of flux on the remaining mess and clean up with a wide tip soldering iron. Don't make it too hot or you will burn the plastic material of the SLI connector.
If its not cleaning up properly, grab some fresh solder and drag it over the connectors. Then try to clean them up again.
10) Once the solder comes off, clean up the remains of the flux with a q-tip and IPA (Isopropyl Alcohol). The q-tip will turn nice and brown/yellow and the contacts on the SLI cable will be nice and silver
11) Now this is the risky part ... grab a butane soldering iron and put a blow torch tip on it. Heat up the PCB, where the connector used to reside, to the point where you see a little bit of smoke coming up (this is the glue melting). You can also heat up the opposite site of the cable where the silver connectors are to help the PCB come off. Just don't overdo it with the heat, or you'll damage the cable. Now you can try to gently pry it off. If you press it against the table and pull down, and it doesn't come off with relative ease that means its not hot enough. Don't make it too hot though or you'll melt the plastic shielding of the SLI cable
12) Once the PCB backing is off, if your cable is a little mangled, apply a little heat and straighten it out. Your fingers will hate you for it but it will make soldering later a lot easier. Also inspect the cable for any cracks in the data paths. If you pulled too hard and the cable wasn't coming off easy and there are cracks clearly visible.... start again
13) Now that the "studded" and "non-studded" cables are ready alight them up. Once again, remember to put the larger heat shrink on one cable and the smaller one on the other.
14) Put the "non-studded" cable on top of the "studded" one so that the pins come through the soldering points.
15) Now solder 4 of the most outer pins (one by one) while holding the cable down. This will make sure the top cable gets as close as possible to the cable below when the solder melts. Then continue soldering the remaining pins.
16) Once the pins are all connected, move the smaller heat shrink to the middle and apply heat.
17) Now move the bigger heat shrink to the middle and apply heat.
18) Enjoy