So i just built this computer, got everything together fine got her running perfect on windows 7 and everything.
After 2 weeks of perfect computing i go to turn on my computer and there's no signal to the monitor;
Have 3 monitors, 1-DVI, 1 Thru DVI adapter and one thru HDMI. I tried all of them and i get no signal
Here's my build;
AMD Phenom II X6 1055T
500W ATX12V Power Supply
HIS Radeon HD 5770 (Juniper XT) 1GB 128-bit
ASUS M4A87TD/USB3 AM3 AMD 870 SATA 6Gb/s USB 3.0 Mobo
Unplugging/holding down power for 30 seconds to reset
Removing CMOS battery to clear CMOS
The computer turns on, all components have power, fan spins on GPU but NO INPUT signal to monitors
I dont have or know anybody with a graphics card to test out
Only option im left with is either calling HIS or Newegg and trying to get my GPU swapped out
Well that power supply is not especially good but I'd like to think it would support your system.
I would try looking at this thread starting at step 22. Since it did work for 2 weeks, unless you have changed something inside the computer recently, you should be able to skip the first part of the guide talking about connecting all the right components to the right places and making sure they have power. Step 22 outlines disconnecting everything except the cpu and heatsink and booting. you should hear some beeps. If you don't, take the mobo back out of the case and breadboard as suggested in the guide. If you get a series of beeps, continue adding components as the guide detpails to diagnose your problem.
If you get through all the steps and the beep patterns change appropriately, then yes, your graphics card is bad. However, if you still get no beeps after removing it from the case and only have the cpu and HSF on the motherboard, The first thing I would suspect, as the guide says, it is your power supply.