Power cable help

Matteus · May 23, 2023

So my PSU only has 1 6 pin PCIe cable, and I want an 8 pin GPU. Should I get a 6 pin to 8 pin adapter, or will it blow up?

Spotty · May 23, 2023

What model power supply do you have? If it only has a single 6pin PCIe connector it is likely very old, or extremely poor quality (probably both).

What graphics card?

Matteus · May 23, 2023

29 minutes ago, Spotty said:

What model power supply do you have? If it only has a single 6pin PCIe connector it is likely very old, or extremely poor quality (probably both).

What graphics card?

It's a cooler master 500w that they don't make anymore. And I haven't really decided on the GPU, probably an RX 5600 XT or a GTX 1070.

Spotty · May 23, 2023

10 minutes ago, Matteus said:

It's a cooler master 500w that they don't make anymore. And I haven't really decided on the GPU, probably an RX 5600 XT or a GTX 1070.

Both the 5600XT and GTX1070 will draw around 150-170W under load, depending on the model.

According to the spec label on that power supply it has two 12V rails. 12V1 is 18A and 12V2 is also 18A. One of them is going to be for the CPU power and the other will likely be for the motherboard, peripherals, and PCIe. 18A max gives you 216W on 12V which is shared across those devices, though the two 12V rails combined are only rated to output a maximum of 360W on 12V and a total combined power of 430W across the entire power supply. Even if it had an 8pin PCIe cable or you used an adapter with a graphics card that can draw 150W+ you might be overloading that 12V2 rail by exceeding the 18A it's rated for (when including other devices powered by the same rail like motherboard, HDDs, fans) or the 360W combined 12V rating. If it only has a 6pin PCIe power connector then that's probably all Cooler Master thinks it can safely handle and want to stop people plugging higher power draw 8pin graphics cards in with it.

Can also tell that since it lacks power factor correction (what it means where it says "W/O PFC" on the label) that it is a low end unit designed to be very cheap, probably wouldn't want to run it close to the maximum of what it's rated for anyway.

I would recommend budgeting for a new power supply when shopping for a new graphics card or looking at graphics cards that draw less power and preferably only require a 6pin connector. If you go up a newer generation of card and the model down (1660Ti, RX 6500xt) you might find some 6pin cards with lower power draw. Just keep in mind that the 6500XT has only a PCIe 4.0 x4 interface so if you're on an older system with PCIe 3.0 or PCIe 2.0 it will be restricted by the lower bandwidth on the x4 link and it won't perform as well as it should. I think most of the 1660Tis will have an 8pin connector but because the total power draw is lower (120W) you might get away with using an adapter there. Though I'd still recommend going the route of replacing the power supply.