The answer is yes and no. Mining Bitcoin with this is useless, don't even attempt it. What you should be doing (and where this thread will be moved) is look for information in the altcoin section.
Another question i have, are these cards even a good choice? I chose them mainly because i have an old 7950 lying around and they are cheap.
It depends on highly what you plan on mining. If you have an old 7950 just lying there, and your electricity cost is fixed then there's no harm into putting that one to work as well.
Now if i bought these cards, how the fuck am i going to fit them onto one motherboard?
You only need enough slots and a certain type of cable called 'Riser'. Here's how USB risers look (but there are plenty of other variants):
https://www.youtube.com/watch?v=sOBxoSQyZFc
http://www.coinwarz.com/cryptocurrency - Mining profitability calculator.
https://bitcointalk.org/index.php?topic=1382920.0 - Here's a thread with a fair amount of replies for choosing GPUs.
Its settled then, assuming that the cards will work together just fine no matter what manufacturer they are from, i will buy a motherboard with 4 gpu slots, 4 usb risers, a cpu and a good PSU. Oh and some fans to keep the rig cool.
Now, which cpu and psu should i buy? Because 4 of these bad are going to pull quite a lot of power.
I use nicehash miner so the profits are calculated by their calculator. Their software automatically changes algorithms to whichever is more profitable at the moment.