Minimum requirements for a mining rig

[Distribution]

I have some spare parts, including hard drives, RAM, and cd drives. I'm talking to a guy about picking up some of his spare parts to build a mining rig, but what are the minimum requirements? How much RAM, etc would I need?

[Garrett Burgwardt]

The only important bits are CPU, Video card and power supply (and case I suppose)

CPU is marginally important, an AMD Duron is gonna gimp your mining, no question about that, but anything moderately new (pentium 4 or newer I'd say) should be good enough.

Video card should be AMD, 5970 and 6990 are the best cards at the moment.

Power supply needs to be high quality because it will be under heavy load at all times.

Case needs to provide good airflow to keep things chilly.

[Distribution]

I have a 5830 card. The guy says he has a Sapphire 550w PSU, 2 GB RAM, AMD X2 3800 processor, a micro-atx mobo with the case. I assume that will be plenty, but I know what happens when I assume.

[Garrett Burgwardt]

The only thing I'd be worried about there is the PSU, because often cheaper ones are rated a bit too high. Still, that sounds like it should work.

[Lardie]

The only thing I'd be worried about there is the PSU, because often cheaper ones are rated a bit too high. Still, that sounds like it should work.

No need for PSU concerns here. I bought a new power supply for my miner (a single 5870) only to discover that under full load and overclocked my entire computer consumes a paltry 207w of power.
A 550w PSU will be more than enough.

[urizane]

Since AMD rates a stock 5870 at 188W, I'd make sure you're not reading the wattage from an UPS.  I've seen two different UPS units from the same manufacturer report the same computer as having two entirely different wattages at the same power state.  One read 140W while the other read 220W.  As far as I know, I haven't heard anyone who owns a Kill-a-watt getting strange results like that.

I'll agree that a 550W power supply would do the job.  So long as you've got an 18A capable 12V rail feeding that 5830, it should run fine.  Just make sure you don't do something silly, like install a PSU with the fan facing downward on the bottom of a case that doesn't have a hole for the fan.  I've seen someone try that once.