Powering a GPU with both a 6 and 8 pin slot

Dains_zoo

Hello All and thanks in advance for helping. 
I recently bought a FATBOY XFX RX590 8GB GPU for my personal build. My power source is a 700W (Cooler Master RS-700-AMBA-D3), but it only has 4pin floppy and 6pin PCI-E slots. I have a PCI express cable that has a 6 and 8 pin connector, but I am fairly certain I cannot plug that in solely, right. I would rather not do anything untoward to my machine as I really want to get back to gaming. 
Do you know what kind of cord I should get? Is there a cord or adapter that can connect 4 pin floppy on one end and 6 or 8 pin on the other? Also, I am using a full tower so I will need longer cords 8-12 inch most likely. 
Thanks again, 
Dains

PowerSpec_MikeW

That would be fine. The only issue you'll ever run into here is if your PSU is multi-rail and the amperage isn't enough on the rail you're connecting it to. Your power supply is a single rail unit, this is preferred, so you don't have anything to worry about. This will actually be labeled on the side of your PSU. You'll notice your unit has 12V = 50A. If it was multi-rail it would have a 12V1, 12V2, ect. At that point you would have a concern of overloading a rail.

So you find amperage from wattage by dividing in by the voltage. On PC's yellow is 12v. So we take a 6+8 pin. 75W on the 6 and 150W on the 8. 225W divided by 12V. Little under 19A. That's against your 50A rail. The card can also draw 75W through the board, about 6.5A.

Ian

Greetings. Looking up your supply online, on the Cooler Master site http://us.coolermaster.com/product/Detail/powersupply/silent-pro-m/silent-pro-m700.html it says it has 2 6+2 PCI-e adapters.

You should just be able to plug those into the video card, use one of the 6+2 cables for the 8-pin, and the other for the 6-pin and the leftover 2-pin part on the 2nd PCI cable can just be unplugged and it should be fine to use.

Dains_zoo

We bought our power supply about 10 years ago and I have lost the extra cables to my wife's organization skillz.
The FatBoy came with a 8-pin to dual female 6-pin cable. I can't tell if that means I need to use 2 6-pin PCIE slots on my power supply to power the 8pin or vice-versa. Either way the cable is too short to reach.What cables do we need to buy? 

PowerSpec_MikeW

You can adapt an 6 pin PCIe into an 8 pin. They have the same number of 12v wires, the extra two pins are grounds. Eliminates crosstalk at the higher wattage, the 8 pin allows double the wattage from 75W to 150W. Generally shouldn't be an issue though, unless it's a very long cable with extensions.

Buy a 6 to 8 pin adapter and just use that one one 6 pin, and the other just connect directly. The alternative is trying to find replacement modular cables, but that's another mess to get into. They're not standard or universal. It varies by the OEM manufacturer of the power supply.

Dains_zoo

I currently have a cable that has a 6-pin that connects to the PSU and goes off into a daisy chain type split. One end of the split is a six pin the other is a 6+2 (8) pin. Could I power my GPU with this one cord?  If so, would that be harmful?

Dains_zoo

Thanks Mike