Dreamcast-Talk.com

One of my Dreamcasts has lately had this nasty habit of powering itself off at random times. Usually I would think it's a heat issue, but the system isn't warm (the exhaust does blow) and it's in a very well ventilated place.

Any ideas?

The most common reason for this (AFAIK) is that the pins on the PSU aren't making good contact. When the PSU board warms up and expands after being on, the PSU pins momentarily lose contact, and the DC loses power. Check the pins to make sure they're fitting tightly and scrape off any gunk that might be on them.

Not sure what happened, but I cleaned off the PSU inside and it ran for over an hour straight (it had been shutting off at about half an hour tops).

It is a common issue and like Ives said make sure to remove PSU and clean the pins and also where the pins connect to the dc mobo.