No video output on boot

[larrycannon]

Hello,

I built a computer recently the system worked fine with the motherboards on board graphics chip but i wanted to use the system for some decent gaming so i added a dedicated graphics card (HD 6770). Now when i turn the computer on soon after turning it off, or doing a simple restart there is no graphics output on the screen and the HDD shows no activity either, only thing which happens is all the fans turn on.

I tried connecting the monitor to both the 6770 and the on board card and there is no display, not even the bios. If i wait long enough the system will run normally again which sounds like it might be a issue with overheating? Thing is the 6770 shouldn't overheat that badly, im not putting it under any stress yet. and why would it effect the rest of the system i.e the on board graphics.

hope someone can suggest something? is there some sort of heat safety switch im tripping? or is the 6770 faulty? maybe it needs exchanging?

Phenom II X4 955
Radeon Hd 6770
4GB Corsair XMS3
Gigabyte GA-880GM-D2H

 

[shortstuff_mt]

It sounds like maybe your PSU can't reliably power your GPU. What PSU do you have? If it's a cheap one that would be at the top of the suspect list.

 

[geekapproved]

Did you plug in the 6pin power cable from the power supply to the video card?

Do you have a 450w power supply with a 6pin video power cable?

 

[larrycannon]

Thanks for the advice, I have a Cit M-500U not exactly the best around, also I'm powering the card using a 2 molex to PCIe adapter, would this make a difference?

Is there a PSU you would recommend? I tried to find a better one but i'm using a mATX case which won't fit an ATX PSU.

 

[geekapproved]

I would NOT use 2 molex adaptors. 1 yes, 2 no.

Tell us which m-atx case you have so were not trying to guess what you have here. Siiigh.

Most m-atx cases take atx power supplies.

 

[larrycannon]

Sorry, not 2 molex adapters i mean one adapter converting two seperate molex cables into one 6 pin PCIe. Badly phrased.

The case I have unfortunately doesn't fit a standard ATX PSU:

www.­xcase.­co.­uk/­product-­p/­case-­x-­case-­x1501a.­htm

I'm looking at this PSU maybe

http://www.scan.co.uk/products/350w-psu-be-quiet-bn134-82-eff-80-plus-quiet-fan-matx-v32-sfx-power

Its hard to find a mATX supply with a high enough wattage, >300W. Choice is pretty limited

 

[geekapproved]

So your saying 2 molex into 1 pci-e? Never seen one of those.


Your problems are understood with the M-atx case. That is why one does not try to build a gaming machine with a M-atx case.

Your pretty screwed. Maybe return the video card for a 6670, that one does NOT require a pci-e 6 pin connector.

 

[larrycannon]

Just an update in case anyone else has this problem, I found a decent replacement PSU ,

http://www.novatech.co.uk/products/components/powersupplies/Silverstone/SST-ST45SF.html#utm_source=google&utm_medium=base&utm_campaign=products

Which fixed everything. Cheers for your help guys.