PCI-E 8 Pin Power to CPU 4+4 Pin-Out

[Annix]

Hi everyone, long time lurker first time poster and first time (this decade) builder. 

 

 I've gotten stuck on what I'm sure will be the only problem I run into and not the first in a series of progressively worse ones throughout this build. 

The power supply I managed to get my hands on is a Thermaltake Madrid 850w 80+ Gold Semi-Modular, unfortunately the board I'm going with requires a standard 8 pin CPU, as well as a 4 Pin CPU / EATX12V_2.

I know some boards can run just fine off of the standard 8 pin without the 4 pin, however from some of the documentation and posts I've read this can be problematic on Asus boards. 

 

I've done some research which shows people solving this problem with Molex adapters which I'd really like to avoid, but as a I have a spare PCIe output from my PSU I figured I could probably just cannibalize a PCIe power cable and re-pin a 4 or 4+4 pin CPU header to make things work. Hopefully this will be safer power draw wise than a Molex or SATA to CPU power cable would. As such I have drawn up (in advanced super professional software definitely not MS Paint) a diagram showing what I'm planning on doing.

 

I'm smart enough to come up with the idea, but way too dumb to know if this is a horrible idea - which is hopefully where you guys will come in. 

 

Is this a viable solution? Is there a safer/more efficient way to do this?

 

In case the horrible perfect illustration isn't clear, I'm planning on going :

 

12 V

PCIe Pin 1   EATX12V_2 Pin 3

PCIe Pin 2   EATX12V_2 Pin 4

 

GND

PCIe Pin 5   EATX12V_2 Pin 1

PCIe Pin 7   EATX12V_2 Pin 2

 

The remaining unused GND, Sense A, Sense B and 12V pins I would probably just terminate in the other half of the 4+4 connector and label "DO NOT EVER USE SERIOUSLY I SWEAR TO GOD".

 

 

 

[Haro]

1 minute ago, Annix said:

however from some of the documentation and posts I've read this can be problematic on Asus boards. 

no? 

it'll work the same way on asus boards 

the 8 pin can provide up to 384w of power  and you wont reach that any time soon with or without overclocking on a normal cooler (aio or air).

[Annix]

3 minutes ago, TofuHaroto said:

no? 

it'll work the same way on asus boards 

the 8 pin can provide up to 384w of power  and you wont reach that any time soon with or without overclocking on a normal cooler (aio or air).

Okay, well let's assume that I need the 4 pin CPU adapter, I've been kidnapped and the only way they'll release me is if I can get PCIe power to safely adapt to 4 pin CPU. Is this the way to do it?

[Jeppes]

1 minute ago, Annix said:

Okay, well let's assume that I need the 4 pin CPU adapter, I've been kidnapped and the only way they'll release me is if I can get PCIe power to safely adapt to 4 pin CPU. Is this the way to do it?

Just tell the kidnapper you dont need it.

[Haro]

1 minute ago, Annix said:

Is this the way to do it?

i mean, technically if i understood you correctly it should work.

do i recommend it? no, no i do not. just use the single 8 pin.

[IC4]

30 minutes ago, Annix said:

Hi everyone, long time lurker first time poster and first time (this decade) builder. 

 

 I've gotten stuck on what I'm sure will be the only problem I run into and not the first in a series of progressively worse ones throughout this build. 

The power supply I managed to get my hands on is a Thermaltake Madrid 850w 80+ Gold Semi-Modular, unfortunately the board I'm going with requires a standard 8 pin CPU, as well as a 4 Pin CPU / EATX12V_2.

I know some boards can run just fine off of the standard 8 pin without the 4 pin, however from some of the documentation and posts I've read this can be problematic on Asus boards. 

 

I've done some research which shows people solving this problem with Molex adapters which I'd really like to avoid, but as a I have a spare PCIe output from my PSU I figured I could probably just cannibalize a PCIe power cable and re-pin a 4 or 4+4 pin CPU header to make things work. Hopefully this will be safer power draw wise than a Molex or SATA to CPU power cable would. As such I have drawn up (in advanced super professional software definitely not MS Paint) a diagram showing what I'm planning on doing.

 

I'm smart enough to come up with the idea, but way too dumb to know if this is a horrible idea - which is hopefully where you guys will come in. 

 

Is this a viable solution? Is there a safer/more efficient way to do this?

 

In case the horrible perfect illustration isn't clear, I'm planning on going :

 

12 V

PCIe Pin 1   EATX12V_2 Pin 3

PCIe Pin 2   EATX12V_2 Pin 4

 

GND

PCIe Pin 5   EATX12V_2 Pin 1

PCIe Pin 7   EATX12V_2 Pin 2

 

The remaining unused GND, Sense A, Sense B and 12V pins I would probably just terminate in the other half of the 4+4 connector and label "DO NOT EVER USE SERIOUSLY I SWEAR TO GOD".

 

 

 

I agree with tofu, this solution is ridiculous, what asus board do you have because I haven’t heard of this. 

[GoldenLag]

33 minutes ago, Annix said:

know some boards can run just fine off of the standard 8 pin without the 4 pin, however from some of the documentation and posts I've read this can be problematic on Asus boards. 

No board that im aware of on a consumer plattform that is either intel 1151 or AM4 knows if both are populated. 

 

As they are both plugged in series(edit: parallell? For some reason my vocabulary is missing words today). Hence just populating the 8-pin will be sufficient. 

[Annix]

18 minutes ago, Jeppes said:

Just tell the kidnapper you dont need it.

lol

 

17 minutes ago, TofuHaroto said:

i mean, technically if i understood you correctly it should work.

do i recommend it? no, no i do not. just use the single 8 pin.

Fair enough, I understand where you're coming from I just like to er on the side of having a safe overhead, though if the 8pin supplies 384w then I'm sure that's enough for the R5 3600 I'll be throwing in there. Out of curiosity, do you know how much extra power the additional 4 pin supplies?

[Haro]

Just now, Annix said:

of having a safe overhead,

the 8 pin is more than enough. 

 

Just now, Annix said:

I'm sure that's enough for the R5 3600 I'll be throwing in there.

more than enough 

Just now, Annix said:

Out of curiosity, do you know how much extra power the additional 4 pin supplies?

afaik, half the current/ wattage capabilities of the 8 pin.

[Annix]

4 minutes ago, GoldenLag said:

No board that im aware of on a consumer plattform that is either intel 1151 or AM4 knows if both are populated. 

 

As they are both plugged in series. Hence just populating the 8-pin will be sufficient. 

 

6 minutes ago, IC4 said:

I agree with tofu, this solution is ridiculous, what asus board do you have because I haven’t heard of this. 

 

This is what I was referring to, in trying to find a pin out I came across this which is for the Maximus VI.

"Do not forget to connect the 4-pin/8-pin EATX12 V power plug. Otherwise, the system will not boot."

 

The board I've ordered is the Asus Strix B550-E. Pairing it with a R5 3600 for now until Ryzen 3 launches. 

 

 

[GoldenLag]

1 minute ago, Annix said:

This is what I was referring to, in trying to find a pin out I came across this which is for the Maximus VI.

"Do not forget to connect the 4-pin/8-pin EATX12 V power plug. Otherwise, the system will not boot."

Thats just reffering to the connectors as a whole, not the supplementary 4-pin. 

[Jeppes]

1 minute ago, Annix said:

 

 

This is what I was referring to, in trying to find a pin out I came across this which is for the Maximus VI.

"Do not forget to connect the 4-pin/8-pin EATX12 V power plug. Otherwise, the system will not boot."

 

The board I've ordered is the Asus Strix B550-E. Pairing it with a R5 3600 for now until Ryzen 3 launches. 

 

 

You see the "/"there? It should work even with only a 4 pin connector.

[Annix]

It does also look like the manual for my actual board is a little less ambiguous, whereas the one above for the Maximus VI says "Do not forget to connect the 4-pin/8-pin EATX12 V power plug" which makes it seems like both are necessary, the manual for the Strix B550-E simply says "Ensure to connect the 8-pin power plug, or connect both the 8-pin and 4-pin power plugs."

 

Look at that, it was me who the idiot all along!

 

That said....still curious to know if my re-pin/diy adapter would work in a pinch. 

[GoldenLag]

2 minutes ago, Annix said:

That said....still curious to know if my re-pin/diy adapter would work in a pinch. 

Well you dont need it in the first place. 

 

That said ive not looked at your suggestion propper as its not needed in the first place. 

 

Also the manual you are reffering to is very much using the word "or". There is not concern to be had. 

 

Also a good 400w unit would have been sufficient for this build. 

[Annix]

1 minute ago, GoldenLag said:

Well you dont need it in the first place. 

 

That said ive not looked at your suggestion propper as its not needed in the first place. 

 

Also the manual you are reffering to is very much using the word "or". There is not concern to be had. 

 

Also a good 400w unit would have been sufficient for this build. 

I'll disagree on the "/" definitely meaning or, I think a fair number of people would read that as to mean both, which I think is why they clarified it to say "or" in the more recent manual. 

 

Much appreciated for the clarification, as much as I was looking forward to a bit of crafty DIY adapter..ing, it's good to know it's not needed. 

 

Absolutely agreed, the 850w PSU was very lightly used and was got for much cheaper than even a semi modular 450w so I went for it despite the overkill.

 

Learning all this has kind of made the extra 4 pin power socket seem a bit unneeded overall, what are the real world scenarios in which you really would need to use one?

[GoldenLag]

Just now, Annix said:

Learning all this has kind of made the extra 4 pin power socket seem a bit unneeded overall, what are the real world scenarios in which you really would need to use one?

Outside of certain HEDT CPU, on consumer sockets like lga1151, lga1200 and AM4, it would be for dry ice or LN2 overclocking. 

[Annix]

2 minutes ago, GoldenLag said:

Outside of certain HEDT CPU, on consumer sockets like lga1151, lga1200 and AM4, it would be for dry ice or LN2 overclocking. 

So, is it's inclusion on consumer non-extreme overclocking boards completely pointless then? Something board manufacturers just include to look like a bigboi?

 

Funnily enough, I did actually find an exact adapter for what I was trying to do myself. Looks like someone's managed to cash in on the very small subset of people that followed my train of thought. 

https://www.amazon.com/COMeap-Detachable-EPS-12V-Motherboard-Seasonic/dp/B07WWWDVG8

 

 

[GoldenLag]

1 minute ago, Annix said:

So, is it's inclusion on consumer non-extreme overclocking boards completely pointless then?

Pretty much. 

 

1 minute ago, Annix said:

Something board manufacturers just include to look like a bigboi?

Small cost to make the board look better. 

 

Its really hard to market a board, not to mention few know what the connectors can actually do.

 

[Guest]

24 minutes ago, Annix said:

So, is it's inclusion on consumer non-extreme overclocking boards completely pointless then? Something board manufacturers just include to look like a bigboi?

 

Funnily enough, I did actually find an exact adapter for what I was trying to do myself. Looks like someone's managed to cash in on the very small subset of people that followed my train of thought. 

https://www.amazon.com/COMeap-Detachable-EPS-12V-Motherboard-Seasonic/dp/B07WWWDVG8

 

 

No.  That's a cable for Seasonic PSUs if you need an extra/replacement EPS12V cable.  This isn't uncommon.

 

But it wouldn't work for you.  Pinout and connector shapes vary from brand to brand of PSU.

 

Your Madrid actually uses the same 8-pin for PCIe/EPS12V as Corsair's.  Something you can buy almost anywhere.  But as others have said, you really don't need it.

[Annix]

45 minutes ago, jonnyGURU said:

No.  That's a cable for Seasonic PSUs if you need an extra/replacement EPS12V cable.  This isn't uncommon.

 

But it wouldn't work for you.  Pinout and connector shapes vary from brand to brand of PSU.

 

Your Madrid actually uses the same 8-pin for PCIe/EPS12V as Corsair's.  Something you can buy almost anywhere.  But as others have said, you really don't need it.

Where did you find the pinout info for the Madrid out of curiosity? Truthfully I've had a hard time finding much documentation or even manuals for it. 

[Guest]

1 hour ago, Annix said:

Where did you find the pinout info for the Madrid out of curiosity? Truthfully I've had a hard time finding much documentation or even manuals for it. 

I got the information from the manufacturer (the actual manufacturer, not Thermaltake).

 

[IC4]

2 hours ago, Annix said:

Where did you find the pinout info for the Madrid out of curiosity? Truthfully I've had a hard time finding much documentation or even manuals for it. 

Jonny guru is like the dad everyone wants in the power supply department. He knows a lot 

[Annix]

10 hours ago, jonnyGURU said:

I got the information from the manufacturer (the actual manufacturer, not Thermaltake).

 

 

[Guest]

8 hours ago, Annix said:

 

There are no secrets.  Many of CWT made PSUs have the same pin out:  http://jongerow.com/Corsair_pinouts/Corsair_pinout_Type_4.htm

 

[Annix]

On 7/10/2020 at 6:09 PM, jonnyGURU said:

There are no secrets.  Many of CWT made PSUs have the same pin out:  http://jongerow.com/Corsair_pinouts/Corsair_pinout_Type_4.htm

 

Thanks very much for sharing this, and the advice given. Now that I know I really won't need the extra 4-pin CPU power I won't go ahead with my re-pin project, but having this documentation is a nice security blanket.