Re: How much power can you pull through the molex connector ?

The problem comes from manufactures no following the specs. A 20 pin mobo connecter should be able to supply 75w total to all the PCIe slots, 24 pin is 150w total. Reference GPU cards are designed to pull no more than 25w from the PCIe slot.

What

I thought they pulled 75W from the slot.

They aren't "supposed" to. But some do. And one reason why you get burned up mobo connections. Most common cause is a loose connection though. That causes a reduction in the cross section available to the current, causing overheating, and in worst case senarios, arcing, sparking, and fires. Tongue

Legacy PCI slots were designed for a limit of 25 watts per slot, but PCI Express is designed for 75 watts per slot. Cheap motherboards can and will burn dramatically when each of 4 or more slots is pulling 75 watts, however a good, well designed motherboard will not. The better designs have the additional 6-or-8 pin connectors near the slots in addition to the main ATX connector.

Correct, I was mistaken. That tends to happen after working 90+ hours in a week. Sorry, my brain is fried. However, I still wouldn't try to pull 300W through 4 PCIe slots with just the ATX mobo connector.