Question Are PCIe-to-8-pin-EPS/CPU adapters safe?

So, I'm usually the first one to say Molex-to-PCIe and SATA-to-PCIe adapters are a fire waiting to happen. But what about PCIe-to-EPS/CPU? Is it safe to use such an adapter if your PSU doesn't have enough EPS/CPU connectors?

That's the short version. The extended, overly verbose version of this follows:
"But, King_V, what the hell do you mean? How many EPS/CPU connectors does one need? It's either a 4-pin or an 8-pin, and most modern PSUs have the 4+4 setup."

So glad you asked! You're right. Normally. But what if it's 12 total pins, a 4-pin near the CPU, and an 8-pin several inches away from that 4-pin? In this case, I was tasked with diagnosing a PC. It's a Dell Alienware (R5, and has a 6th gen i7). It's a little bizarre. It has dual PCIe x16 slots, and it has a 4-pin EPS/CPU connector near the CPU.

I was told that the previous owner had fired it up with the PSU switched to 240V rather than 115V, and Bad Things happened, which included sparks flying from the PSU. Also note that it's not the original PSU that came with the Alienware, but an Apevia (yes, you may cringe now).

So, I decided to try with a known good PSU I had, and proceeded to remove the old one. Disconnected various things, along with a 4-pin EPS/CPU connector, and . . .something else. An 8-pin connector above the uppermost PCIe slot labeled GPU_PWR. That was slightly stubborn coming out.

Turns out that: without the EPS/CPU connector in, the PC won't boot, and the CPU fan won't even spin up. Without the GPU_PWR connected, you can't get video out of a video card, not even a lowly GT 1030 DDR4. The GPU's fan won't even spin up in that case.

So, I tried to plug in a PCIe 8-pin to that GPU_PWR on the board, and it wouldn't go in. I realized the shape of the plug was a little different. I looked back at the Apevia, and it only had ONE connector that was 8-pin, and that was the PCIe.

Some research revealed that the GPU_PWR connector on the Alienware's motherboard is exactly the same as an 8-pin EPS/CPU connector. Further, the previous owner of this machine had FORCED the 8-pin PCIe into it. No wonder things went unpleasantly.


My trick to test the machine was to plug in a regular PSU, with the 4-pin on the EPS/CPU, then with an extender for the 8-pin EPS/CPU from another power supply connected to another PC, provide power to the GPU_PWR connector, then power both machines on. That's how I was able to determine the Alienware was working, do a clean install of Windows on it, etc.


So, the new owner of the Alienware simply has to get a power supply. They'd need to either buy an original Dell type PSU for Alienware, or get a standard PSU, and a PCIe-to-EPS/CPU adapter, or, as the third solution, get a modular PSU, but then also purchase an additional EPS/CPU cable for that specific brand/model of modular PSU. Hence why I'm asking about the adapter - plus, I know that the new owner isn't a hardcore gamer, and won't be doing a multi-GPU setup. Their gaming needs are quite modest.
 

Zerk2012

Titan
Ambassador
So, I'm usually the first one to say Molex-to-PCIe and SATA-to-PCIe adapters are a fire waiting to happen. But what about PCIe-to-EPS/CPU? Is it safe to use such an adapter if your PSU doesn't have enough EPS/CPU connectors?

That's the short version. The extended, overly verbose version of this follows:
"But, King_V, what the hell do you mean? How many EPS/CPU connectors does one need? It's either a 4-pin or an 8-pin, and most modern PSUs have the 4+4 setup."

So glad you asked! You're right. Normally. But what if it's 12 total pins, a 4-pin near the CPU, and an 8-pin several inches away from that 4-pin? In this case, I was tasked with diagnosing a PC. It's a Dell Alienware (R5, and has a 6th gen i7). It's a little bizarre. It has dual PCIe x16 slots, and it has a 4-pin EPS/CPU connector near the CPU.

I was told that the previous owner had fired it up with the PSU switched to 240V rather than 115V, and Bad Things happened, which included sparks flying from the PSU. Also note that it's not the original PSU that came with the Alienware, but an Apevia (yes, you may cringe now).

So, I decided to try with a known good PSU I had, and proceeded to remove the old one. Disconnected various things, along with a 4-pin EPS/CPU connector, and . . .something else. An 8-pin connector above the uppermost PCIe slot labeled GPU_PWR. That was slightly stubborn coming out.

Turns out that: without the EPS/CPU connector in, the PC won't boot, and the CPU fan won't even spin up. Without the GPU_PWR connected, you can't get video out of a video card, not even a lowly GT 1030 DDR4. The GPU's fan won't even spin up in that case.

So, I tried to plug in a PCIe 8-pin to that GPU_PWR on the board, and it wouldn't go in. I realized the shape of the plug was a little different. I looked back at the Apevia, and it only had ONE connector that was 8-pin, and that was the PCIe.

Some research revealed that the GPU_PWR connector on the Alienware's motherboard is exactly the same as an 8-pin EPS/CPU connector. Further, the previous owner of this machine had FORCED the 8-pin PCIe into it. No wonder things went unpleasantly.


My trick to test the machine was to plug in a regular PSU, with the 4-pin on the EPS/CPU, then with an extender for the 8-pin EPS/CPU from another power supply connected to another PC, provide power to the GPU_PWR connector, then power both machines on. That's how I was able to determine the Alienware was working, do a clean install of Windows on it, etc.


So, the new owner of the Alienware simply has to get a power supply. They'd need to either buy an original Dell type PSU for Alienware, or get a standard PSU, and a PCIe-to-EPS/CPU adapter, or, as the third solution, get a modular PSU, but then also purchase an additional EPS/CPU cable for that specific brand/model of modular PSU. Hence why I'm asking about the adapter - plus, I know that the new owner isn't a hardcore gamer, and won't be doing a multi-GPU setup. Their gaming needs are quite modest.
If I read the post right you have a 4 pin, 8 pin and 24 pin all for the CPU and motherboard correct?

The 8 pin should not be needed if the video card has a power plug on it. 4 Pin CPU, normal 24 pin, the 8 pin should be for the PCI-E slots.

https://ip1.i.lithium.com/ce5ea0efc347b3868c7a568325253d29b0ad6bad/68747470733a2f2f766a61756a35383534392e692e6c69746869756d2e636f6d2f636f6d6d756e6974792f732f6c656761637966732f6f6e6c696e652f616c69656e776172652f32303530355f7236612e4a5047
 
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Reactions: JoBalz
It's weird. The MB has a 4-pin EPS for the CPU, a 24-pin for the main power, and an 8-pin EPS for the GPU(s), and if the 8-pin EPS isn't plugged in, the computer will not let you use an add in card. Of course, if the video card has PCIe connectors, I assume they also must be used above and beyond that weird MB 8-pin GPU_PWR thing. I mean, they're just speculation on my part given the behavior when the GT1030 is installed.

My usual concern when using adapters is with the draw being more than what the source is designed for... But I have no idea if that's the case here.
 

Viking2121

Distinguished
I personally never had an issue with Molex to PCIE power, or Molex to sata power, my Server has a few since the PSU didn't have enough. I also made me a 8 pin EPS to dual EPS cable and its been fine for the last 3 years with dual 8 core Xeons in it.

Though I wouldn't go powering a power hungry CPU or GPU with adapters, I mean powering something other than a mid tier GPU with such adapter I would feel uncomfortable.

In my case both my Xeon's are 90 watt parts, I can't see both of them using so much power where my adapter would be a problem, I wouldn't do it on anything more power hungry like my Threadripper.

HDD's doesn't use a ton of power so I don't have an issue with them, unless they crimp job in the connector is crap.

I also made a few molex to 3 sata power adaptors, old leads I cut off a dead PSU and added a molex plug to it. I like living on the edge I guess lol
 

JoBalz

Honorable
Sep 1, 2014
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I could swear I've seen a motherboard with those same power connectors, but it was one of the high dollar board for power hungry systems.

It sounds like replacing the power supply might not be a bad idea. Go with a good brand modular, then pick up the extra cable you need at a cable modding store such as https://usstore.cablemod.com/ . The better stores will not only build custom cables based on the model of PSU you have, but also offer PSU specific cables. Some have them in packages which would be overkill if you only need the one, but many also will do a custom built cable for your specific PSU. If you go that route, check where the cable is made. One company manufactures their custom cables in Hong Kong, so you have the additional shipping time. Others do it within the US, which would be quicker (at last, if you're in the US ;))
 

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