What to do with my old PC?

I'm building a X99A system in the fall, and trying to figure out what to do with my current AM3+ 990FX system. I thought about just using it as a HTPC in my living room, which I don't use often, so it'll collect dust. I then thought about using it as a media server, but not sure if it's really power efficient, and I'd rather not leave it on 24/7 if it's going to hog power. (currently live in Germany, and electricity here isn't that cheap) Any recommended ideas?

Anywho the hardware I have:
CPU: AMD FX 8350
Memory: 16GB DDR3 Corsair Dominator
Motherboard: Asus Crosshair V 990FX
Video Card: Nvidia GTX 680 4GB
SSD: 128GB Corsair P128
Hard Drive 1: WD Velociraptor 300GB
Hard Drive 2: WD Velociraptor 300GB
Hard Drive 3: Samsung 500GB
Hard Drive 4: WD Green 1.5TB
Optical Drive: LG Blu-Ray Drive
Power Supply: Enermax 1050 Watt (6 years old)
Case: Cosmos II

Personally I'd sell it, its overkill for a secondary pc.

Keep drives and memory, and then sell everything else. After that you can buy cheap motherboard with integrated Intel Atom processor/graphics, new power supply and smaller case. Combine everything and you get media server that barely uses any power.

Use it as
-Server.
-2nd gaming PC for friends to lan with.
-Dedicated linux computer.

or something else.

If you don't want to sell it, maybe if you are feeling generous, donate it to a friend without a gaming pc, who couldn't otherwise afford one. I did that once, but it was like a $500 system I built so long ago. Im not rich, I just wanted to help a friend at the time.

Server/Media Center PC is always nice to have though if you like to sit around with people and watch tv shows/movies.

I always have an extra GPU for my systems my gtx560ti has come in handing during an RMA when I had an important deadline but if you need $150 sell it. You could get another $150 for the mobo cpu. $50 for the case. Package deal with ram,gpu some might pay $500 with gpu $250-300 without. That will get almost enough money for your new cpu 5820k and a mobo AsRock. If you use this for work keep the gpu or buy evga they have the best RMA i have dealt with sending me a new unit before they even get my broken one. Im not sure what stuff gos for in Germany you may get more money.