Mac Pro powers/boots up but nothing on screens?

[jesuslovesacid]

I switched my mac pro on a couple of weeks ago and it powered up, then booted (made the mac boot noise) but there is nothing on my monitors.

My monitors work fine (tested) I have tried fixing permissions in target disc mode, fine. CD drives open.

I was told the problem was the graphics card - I received my new graphics card today and installed it but still the same problem - nothing on screen

Please help - I pulling my hair out trying to figure this out. I live in Ibiza and no one knows anything about mac's here

 

[RemarkabLee]

Try turning the Mac on and immediately hold the CMD + ALT + P + R keys down and wait for the SECOND bong.

This resets the PRAM.

If this works, I'll take a flight to Ibiza and be the local Mac tech support

 

[jesuslovesacid]

Tried this but never got a second bong - what is PRAM?

 

[iBug2]

I switched my mac pro on a couple of weeks ago and it powered up, then booted (made the mac boot noise) but there is nothing on my monitors.

My monitors work fine (tested) I have tried fixing permissions in target disc mode, fine. CD drives open.

I was told the problem was the graphics card - I received my new graphics card today and installed it but still the same problem - nothing on screen

Please help - I pulling my hair out trying to figure this out. I live in Ibiza and no one knows anything about mac's here

You can use the computer 100% in Target Disk Mode?

I suggest taking the computer to the nearest apple repair so they can do the diagnostics. Which graphics cards do you have at home to test?

 

[jesuslovesacid]

So it turns out the graphics card I ordered wasn't complatible - I have been told that mac graphics card rarely fail so on advice I put the original ATI Radeon HD 2600XT back in and did some more testing and I have made a very interesting discovery - After trying target disc mode and single user and all that other jazz nothing came up on the screen. Also sometimes target disc mode worked and sometimes it didn't - It turns out that when the monitors are plugged in nothing happens - ie it wont boot in target disc mode / doesnt fully boot (switches off instantly when pressing power off instead of having to hold for a few seconds) But when monitors are plugged out it boots fine

What does that mean??