Member Avatar for 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

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Dani AI

Generated

As described, the system boots when the card’s supplemental 6‑pin connector is left unplugged but dies the instant that connector is attached. That behaviour is not normal: it usually means either a hard short or fault on the card or its power lead, or the PSU’s protection is immediately cutting output when the card asks for additional current. was right to flag power as a suspect, but the immediate shut‑off points more toward a short or miswired connector than just an undersized supply.

Try these checks in order (safe, fast, and isolating):

  • Inspect the card’s 6‑pin socket and the PSU cable closely for melted plastic, bent pins, burn marks or a burnt smell.
  • Swap to a different PCIe power lead or a different native PCIe header on the same PSU (avoid long Molex-to‑PCIe adapters for testing if possible).
  • If available, test the GPU in a known‑good PC. Equally useful: test a known‑good PCIe card with the suspect PSU in your machine. That quickly tells you whether the card or the PSU/motherboard is at fault.
  • With the card disconnected and power removed, use a multimeter (continuity/ohms) to check for a near‑short between the card’s +12V pins and ground. A very low reading suggests a shorted regulator or component on the card.
  • Bench the motherboard outside the case on a non‑conductive surface to rule out a chassis short, reseat the card and connectors, and clear CMOS as a routine extra step.

Safety/caveats: always unplug mains before probing, avoid opening the PSU (dangerous), and don’t rely on cheap adapters for long‑term use. If the card shows a short or fails the cross‑system test, it’s almost certainly a hardware failure and should be RMA’d or replaced. If a different GPU works and the suspect card fails elsewhere, focus on replacement; if every card trips the PSU, the PSU or motherboard power circuitry needs attention.

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Member Avatar for 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)

Member Avatar for 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.

Member Avatar for 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.

Member Avatar for 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.

Member Avatar for 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.

Member Avatar for Arahmon

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

That didn't work either.

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