Quick update to the Rev 1.3 spec

3) GPUs in parallel

As couple of you guys advised me to try it (thanks again!), I'm going to include this in this revision too.

Originally wasn't in plan only because I had nothing else to order from highflow but since I can get DDC 3.25 (PMP-400) only from there, I've got more sli links too.

Really looking forward to see the flow with these improvements. Just hoping DDCs won't be too loud.

The only downside is this will push completion date for next week as I won't have all parts until Monday - but hey, good things come to those who wait