I used to buy old broken computers, fix them up, and sell them as working for a small profit but after setting into my new career path I haven't had time to continue with this hobby which has now left me with close to 25 computers/laptops/macs sitting in my basement that are mostly perfect working computers, just old and no use to me so I'm wondering what kind of use I could have for all of these with mining altcoins.

I was going to set aside an area in one of the garages and hook up all of the computers to run 24/7 altcoin mining with both cpu and gpu at once but I'm not big on the knowledge for this or what's needed for each one.

The property is run entirely on solar and wind so hydro usage doesn't matter at all, I can leave them all on without making a dent in it but I don't know what kind of programs I can use for CPU mining or GPU mining, I would like to do both at once and then maybe run a portable air conditioner to cool the garage all summer so over heating shouldn't be a problem either.

What kind of restrictions would I be looking at for types of CPU's? Some of them are as old as Pentium 4's with onboard graphics, others have some older Radeon GPU's, small old Radeons, around 128mb at most, the majority are 32mb and 64mb gpu's, both Nvidia and ATI. Most of them are Intel based CPU's but I think three or four of them are AMD, I also have a bunch of old Mac's I would like to do something with along the lines of altcoin mining. There's G3 iMacs, G3 iBooks, G4 PowerBooks, G5 iMacs, eMacs, MacBook, some MacBook Pro's, and I also have my ASUS G75 running right now and I have three 27" iMacs running too so I am mining some altcoin with those but I would like to put all of these old computers to use since they're just sitting there anyways and hydro doesn't matter.

It would be nice to have them all sitting there, AND doing something but I don't know what to look for when it comes to both Intel and AMD CPU mining, as well as both Nvidia and ATI GPU mining. What kind of restrictions are there for these old computers? How far back can I go before a CPU or GPU won't be supported to mine altcoins? What would be the best all around mining program that would perform well for all four types of mining I would be aiming for.