mac pro won't come out of standby
My 2009 mac pro which is running Yosemite is having trouble coming out of standby. The monitor says no signal (sometimes, getting more frequent) and I'm forced to restart the computer. Some of the time the computer fan only runs during the restart and the not the startup noise, also forcing me to restart until it works. Usually 1-2 tries. Picture below shows the monitor half black and pixelated from the screenshot. It goes in and out of the black and the pixels for about 30 seconds before going completley black. This is getting frustrating. What is the problem and can it be fixed?
Mac Pro, OS X Mavericks (10.9.2)