Building big systems is so much fun. I love mods that involve massive multiblock structures.
An especially extensive computer/crafting system can be a MASSIVE drain on power... laser drills as well, which is what I plan on putting into space. Having several quarryplus rigs going at once is a HUMONGOUS drain on power in particular, but hopefully we're almost done with that, as it's also a huge resource hog on the server.
But really, not too much beyond laser drills really can drain this kind of power generation. I just like building big things haha