Monitor doesn't turn on after changing graphics card

[Demerara]

Motherboard: DP67DE
PSU: Seventeam 650W
Old graphics card: EVGA GTX 570
New graphics card: Gigabyte GTX770

My computer always worked fine and never had a problem before. I just wanted to upgrade the graphics card.
So, I installed GTX770, but monitor didn't turn on. Everything else is working aparently fine. The fans are spinning, motherboard led is on, I heard a beep when turn on pc...
So I reinstalled GTX570 and turned on the computer. It started ok and monitor displayed fine. For a test, I uninstalled the driver and put GTX 770 back. Result: problem persists, monitor doesn't turn on.
I was thinking it was a PSU problem. Maybe it doesn't support the card. I uninstalled GTX770 and considered buying a new PSU.
So, to finish, I reinstalled GTX570 and, for my surprise, now the same problem occurs with it and monitor doesn't turn on anymore, it only keeps the standby led on. Now I'm thinking it can be a driver problem, but how can I install the driver again if monitor doesn't display anything? Or maybe I'm doing something wrong, considering I'm a noob.
Any ideas? Thanks in advance.

 

[byza]

You usually need to reset the CMOS when you install a new GPU. Turn off your PC, install the new card, clear CMOS, turn it on and it should be good.

 

[Demerara]

You usually need to reset the CMOS when you install a new GPU. Turn off your PC, install the new card, clear CMOS, turn it on and it should be good.

I made a cmos clear using the jumper and the monitor still has no signal.

 

[byza]

Have you tried resetting CMOS with the old GPU or using intergrated GPU?

 

[Demerara]

Have you tried resetting CMOS with the old GPU or using intergrated GPU?

With the new one. My motherboard does not come with integrated graphics.

 

[byza]

The graphics would be intergraded in the CPU not the mobo. In any case i'd try resetting the CMOS with the old card, see if you get picture back, then it might be a power issue.

 

[Demerara]

The graphics would be intergraded in the CPU not the mobo. In any case i'd try resetting the CMOS with the old card, see if you get picture back, then it might be a power issue.

Ater resetting the cmos witt the old graphics card, the monitor didn't turn on.

 

[byza]

Have you made sure that you are plugging the monitor into the GPU? Might seem silly but it's pretty easy to accidentally plug into the motherboard and you won't get any image if a GPU is installed. If you have checked that, remove both GPUs and try resetting the CMOS and using intergrated graphics. Just plug the monitor straight into the motherboard. If that doesn't work your going to have to do some more annoying troubleshooting like testing the monitor on another device to make sure thats not the problem, testing the PSU to make sure it's ok and maybe breadboarding.
http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems

 

[Demerara]

Problem solved!
I called a specialist and he told me there's a bad contact in DVI cable. After reconnect it a lot of times and move cable to some directions, the monitor displayed again. Then, he installed gpu drivers and everything is working fine by now. But I have to avoid touching DVI cable to keep monitor displaying. And tomorrow I'll buy another connector/cable.
Thanks for your responses, byza!

 

[byza]

No problems, I'm glad you got it sorted out.