After replacing a power supply where the fan was not turning, and replacing a broken fan in the case, the computer now starts up fine, but the power shuts off after about 3 minutes. Sometimes after restarting, there is a message that "the cpu experienced a thermal issue (overheating)"
All fans, including the one on the cpu are running. I've used compressed air to clean all the fans. This computer has two large video cards, and so uses a 1000V power supply.
Any suggestions as to why it would be overheating when all cooling fans are working?