6870 black screen on new build, power issues?

[GizmoTheMogwai]

Just built my new i5 system, and everything seems to be working apart from the graphics card. Sapphire 6870 bought from OCUK.


I've tried with VGA/DVI and HDMI, and still only a black screen. I have disabled onboard gfx in the bios to no avail. The fans seem to be working fine, but that's the only sign i'm getting from it.


I have a OCZ ModXStream Pro Power supply - 600 Watt. Now, this 6870 requires 2 6 pin connectors, so I am using the old PSU to GPU 6 pin I was using on my 5750.

I am currently connecting this;

The cables on the far right are the ones I am using, but only using one of the molex connectors alongside my other PSU to GPU cable.

But only using ONE molex as my friend told me connecting 2 would create a circuit and blow **** up. Then, from that one molex, it's going into the connector and into the GPU, alongside the old power cable.


Very confusing and hard to explain, but I am wondering if I should be using both molex connectors to deliver power to the GPU?


Would appreciate a diagram or quick sketch-up of what the cabling should be like greatly!

 

[Cold_And_Miserable]

It's more likely the card is DOA.
It's still worth a shot connecting the 2 molexes to the 6pin.

When I didn't plug in all the power connectors on my last ATi card it booted with a message asking to connect the extra power cable so I imagine if the card was working it would have done this.

edit: Check the BIOS has the setting for booting from a PCI/PCI-E card selected. Also try using the onboard VGA if all else fails and see if the card shows up in Windows.

 

[GizmoTheMogwai]

It's more likely the card is DOA.
It's still worth a shot connecting the 2 molexes to the 6pin.

When I didn't plug in all the power connectors on my last ATi card it booted with a message asking to connect the extra power cable so I imagine if the card was working it would have done this.

So, am I right in thinking that using connecting 2 molex adapters isn't going to explode anything? It does seem like it is creating a circuit...

 

[Cold_And_Miserable]

So, am I right in thinking that using connecting 2 molex adapters isn't going to explode anything?

It's perfectly safe but I don't think it will make any difference. It's just putting them in parrallel to split the current.

 

[GizmoTheMogwai]

Not sure what to do now... I think the GPU may be faulty.

 

[Cold_And_Miserable]

Well, I tried the 2 molex pins at the same time and I got a loud high pitched squeal. Tried loading up my computer and now it doesn't post and reboots...


Not sure what to do now...

I thought you already said it wouldn't post AKA a blackscreen ? Or do you mean it won't post using the onboard VGA (by reseting the BIOS first) ?


Where does the high pitched squeal come from? The card, mobo or PSU?

Do you have another highpower card e.g. 5870 to rule out the other components? Is the PSU definitely sound ?

Have you tested the card in another computer?

 

[GizmoTheMogwai]

I took the GPU out, and it isn't posting by onboard VGA, yes. It just turns on for a second or two, then off and rebooting.

 

[Ovr]

Sounds like you've missed a motherboard power connector?

 

[spenncerr]

This is the same issue I was having earlier today, weird fix for me was this:

I was using VGA -> DVI converter which came with the motherboard and I was black screening, but fans were still running. I simply switched back to my old VGA -> DVI converter and it worked fine.

Not sure if you're using the converter or not, but that's what worked for me.

 

[Doug]

I took the GPU out, and it isn't posting by onboard VGA, yes. It just turns on for a second or two, then off and rebooting.

Thought you'd disabled the onboard video?
Cleared cmos to start from scratch?