Question

[NiceSoft12]

If I have a lot of old computers like pentium II's and such, could I put them to good use by using them to mine (considering cost, time, and electricity)?

Obviously they are not good to sell or anything.

[hurricandave]

NO!

[Bizmark13]

Nope.

Bitcoin is can only be profitably mined with ASICs. Some coins such as Litecoin and Darkcoin are mineable with GPUs (although scrypt ASICs are now available for Litecoin which are far more efficient than GPU mining), and there are CPU coins which can be mined with CPUs - here is a list of them.

But I wouldn't use a Pentium II for mining CPU coins either. You would need a recent processor to mine CPU coins - at least, if you want to be profitable. Just like the way you wouldn't use an Nvidia card from 1997 to mine GPU coins.

[Glizlack]

if your wanting to mine say x11, x13, or x15 or a few other algo's it would work assuming you have a pci e slot to run a graphics card. I do this with an old athlonx2 4600. Works fine power draw isn't bad.

Steve

[Bitsaurus]

Unfortunately those older computers don't really support modern GPUs so you can't GPU mine.  The CPUs are too old to mine CPU coins since they don't have the instruction sets.

The only thing it would be good for would be hosting some ASICs, and even then those CPUs are so old you cannot run a 64 bit OS, only a 32bit OS.

So in short, no you can't mine.  Sell them for a couple bucks.

[Relnarien]

If I have a lot of old computers like pentium II's and such, could I put them to good use by using them to mine (considering cost, time, and electricity)?

Obviously they are not good to sell or anything.

Costwise, no. Mining for Bitcoins with anything other than ASIC rigs is no longer profitable and is therefore not recommended. You won't even be helping secure the blockchain by doing so because a single overclocked U2 can generate more hashes per second than an entire room full of Pentium II's (assuming that you intend to mine via CPU hashing only).

If you really have your heart set on CPU mining, then I recommend taking a look at x11-based coins.

Alternatively, you can use those computers for GPU mining. Some Quark-based coins can still be mined fairly easily with a decent GPU rig.

[300]

Unfortunately those older computers don't really support modern GPUs so you can't GPU mine.

This. A Pentium II would be from the 1997-1999 era. Modern graphics cards use the PCI-e interface which only started to become available from about 2004 onwards.