4th GPU with molex adapters ?

[ellishughes12]

Hi,

 

If I have a 1000w psu with only 6 pci-e connectors is it safe to run a 4th gpu with molex adapters?

 

The psu is only running the gpu's nothing else so I'm guessing wattage won't be too much of a problem.

 

Btw gpu's will be 4x 970's

 

Thanks

[Pesukarhu]

A 970 is rated at 145w. That means it is going to use about 12a at 12v. 4x that and you get 48a @ 12v. Check the specs on the psu to see what is the maximum amperage for 12v. If it is rated over 50a you could do it. If the psu has multiple 12v rails, you should use a 8pin cpu to pci-e adapter instead to spread the load. Or check the 12v lines with a continuity tester (multimeters usually have one) to see which ones are on separate rails.

 

A molex connector is rated at 8.5a. The adapters usually have two molex to one pci-e and you would have two adapters, so two adapters could carry a total of 34a without catching fire. (in theory at least...)

 

But before you try it, check that the adapters have been properly crimped by pulling the wires individually (but not too hard, the wire is quite thin after all). When you install it, put the gpu under full load and keep an eye on the adapters, if they get hot dont do it. If you will leave this setup running alone (with load) dont put it under a curtain or a similar easily flammable thing just in case.

Common sense is useful when dealing with these, if it smells, feels bad when plugging in etc. dont use it.

[ellishughes12]

5 minutes ago, Pesukarhu said:

A 970 is rated at 145w. That means it is going to use about 12a at 12v. 4x that and you get 48a @ 12v. Check the specs on the psu to see what is the maximum amperage for 12v. If it is rated over 50a you could do it. If the psu has multiple 12v rails, you should use a 8pin cpu to pci-e adapter instead to spread the load. Or check the 12v lines with a continuity tester (multimeters usually have one) to see which ones are on separate rails.

 

A molex connector is rated at 8.5a. The adapters usually have two molex to one pci-e and you would have two adapters, so two adapters could carry a total of 34a without catching fire. (in theory at least...)

 

But before you try it, check that the adapters have been properly crimped by pulling the wires individually (but not too hard, the wire is quite thin after all). When you install it, put the gpu under full load and keep an eye on the adapters, if they get hot dont do it. If you will leave this setup running alone (with load) dont put it under a curtain or a similar easily flammable thing just in case.

Common sense is useful when dealing with these, if it smells, feels bad when plugging in etc. dont use it.

Thanks for the info, the psu is rated at 83.3A, its a single rail 12v rail.

 

Since it isn't going to be using the cpu connector at all would it be better to use the cpu to pci-e connector (didn't even know these existed lol) instead. Molex is my last resort.

[Pesukarhu]

3 minutes ago, ellishughes12 said:

Thanks for the info, the psu is rated at 83.3A, its a single rail 12v rail.

 

Since it isn't going to be using the cpu connector at all would it be better to use the cpu to pci-e connector instead. Molex is my last resort.

I would use the cpu adapter because it removes cable clutter. However they seem to be rarer so you might have to use molex. I think molex could carry more current but it also may not have as good electrical contact as the cpu connector. Shouldn't matter too much which one you use.