One of them does that and we know it's the motherboard. The model is the R3000 and is over a decade old. The only reason we keep it is that it's twin is also a R3000 so we have a few spares. Machines that old are usually not repaired.
When I turn it on it comes up. Shut down unexpectedly. No matter what way to try and start up it just runs through pages of mysetup stuff and that is it. I can't even sign in. Please help