Old(ish) BTC kit - repurpose?

Hi folks, like a few people I guess, I have some old BTC mining kit around which I'd like to repurpose to a dedicated cracking rig - personal use/research/CTF work etc. 

I have:

• Core i5 CPU (1155)
  
• 8 Gb RAM (2 x 4Gb)
  
• Open case (this one)
  
• and a R9 280x GPU
  

Currently dont have a mobo due to cannabalising the rig to make a family member a PC....but will be getting a suitable one very soon. 

I understand the GPU is a little elderly but should be OK for occasional use as above. I think I will need LTS version of linux rather than the latest version?

Any tips/tricks/ideas to make this as effective as possible? I'll be running this in a cool workshop and the open case/non permanent use should be OK for heat I think?

Cheers all

bowser