yeah - it just runs your cpu at 100% capacity, and will stop if an answer provided is wrong (CPU made an error).
Of course, your CPU can plain stop during this, and I've seen CPU's die in prime95 testing, but if you're at 2.3GHz that shouldn't be too far for a 3000+ (500MHz right? Correct me if I'm thinking of something else).
Just check it every couple hours, but 12-24 hours should let you know if it's stable.
If it's already unstable then it'll immediately fail the calculation - then I'd turn it down