Building a Mining Rig?

[IlbiStarz]

Hey guys,

So I'm thinking about building a sidekick mining rig, with something like 5870's or 5850's in it. If I'm planning to get multiple cards, which mobo should I get for them? Should I Crossfire or not?

Also, people say when building a rig, you should get the least powerful core. However, when mining, doesn't the CPU get stressed? Are you sure that the CPU isn't used at all?

I'll post more questions later if I have them.

Thanks

[Convery]

If you get a Sempron 145 (second cheapest) you could 'unlock' it to a dual core. That should be more then enough for any rig :3

[IlbiStarz]

Which mobo should I get? What's the most cost efficient mobo for getting multiple cards? 3 way, 4 way, etc?