I'm only able to use it once a day. When I try turning it on, it starts but the fan doesn't, so then it just shuts off. Help?
which mac pro? what type of memory? graphic card?
open the side door - any red lights on?
reset SMC - unplug everything. power and kb/mouse etc then hit power button for 10 seconds only. wait 60 seconds and reconnect kb/mouse, power and monitor.
you could hve bad ram or gpu
could have dust and if you don't have ups you better have excellent power and never see an outage or dip/brown out - hard to do sometimes in heat of summer and power demands