Computer Wont boot with SLI Graphics Plugged in

[Arahmon]

Hi all,

Hope this question hasn't been answered already, but I am having some serious issues with my PC.

Basically it won't turn on when I plug in the 6 pin power connector into my 8800GT. Both the CPU and GPU fans rotate very slightly then everything shuts off (then nothing works after that).

It will still power up and work if I don't plug in the SLI power, but obviously this is far from ideal. Everything works fine if I do this, and I have no problems.

The funny thing is it was working for a week then all of a sudden while I was on the 'net it just shut down and wouldn't start up again.

I have replaced the power supply with a 550W Coolermaster Extreme supply but this has not helped.

My PC is:

Gigabyte P35 - DS3 Motherboard
Gigabyte 8800GT 512MB
Intel Q6600
2GB Kingston 800 DDR2 RAM
1 Sata HD
2 DVD Writers.

Any help you could provide would be greatly appreciated.

Thanks

[jbennet]

550w isnt enough for SLI with two 8800GT 512MB

you need a good, expensive power suppy, of 650w - 850w , with at least 2 +12v rails, providing at least 18a each (20+ is better)

[Arahmon]

Sorry for the confusion, but I only have one 8800GT. As I said it worked fine for a week, with only 430 W and I now have more power.

[jbennet]

oh

It will still power up and work if I don't plug in the SLI power[/quote[]

for one, it may be ok but it will brown out under high load. the pci-x bus can only provide about 70w of power.

[Arahmon]

Any ideas why it was working for a week with a less powerful unit, but now as soon as I plug in the extra power connector for the card (with a new more powerful supply) it wont even start.

I am not sure it is the PSU at all, and think it might be the card.

[jbennet]

yeah could be the card
are yo sure you are plugging in the right one - theres another connector that looks like the pci-x one but isnt.

[Arahmon]

Yea. I also tried a converter that takes two of the other connections and connects to the power.

That didn't work either.