Modular PSU confusion

[DemiGod]

Hey guys, dumb question. It was my first time using a modular PSU. And what weirded me out is that pcie cable and cpu has no markings and are exactly the same... the only way I was able to tell them apart was by looking is it connected of 4+4 or 6+2 (by little indent).... So first question, maybe you guys know how to differentiate these cables ?

 

 And second one. My Motherboard has 16 pins (2*8) on the motherboard, and the cpu cable is 8 at one side and 2+8 on another side, how do I even connect it ? Two at psu ant one at cpu or 2 at motherboard and one at psu ? Or I just leave one hanging and I connect 2 cpu cables :?

[filpo]

5 minutes ago, DemiGod said:

maybe you guys know how to differentiate these cables ?

there should be a label on the side of the cables like this (on either end, also this is on my rm850)

 

[filpo]

9 minutes ago, DemiGod said:

And second one. My Motherboard has 16 pins (2*8) on the motherboard, and the cpu cable is 8 at one side and 2+8 on another side, how do I even connect it ? Two at psu ant one at cpu or 2 at motherboard and one at psu ? Or I just leave one hanging and I connect 2 cpu cables :?

connect the 2+8 side to the psu where it say 'CPU'. Then connect one of the 8 pin cables (you should have two) to the motherboard, then rinse (obviously don't actually rinse) and repeat 

[DemiGod]

1 minute ago, filpo said:

there should be a label on the side of the cables like this (on either end, also this is on my rm850)

 

That is the thing there is nothing I just took another look it's gigabyte 850UD.... No markings... At all. But Well I figured out it by taking a very good look at the pin themselves, but I am still not sure how connect it to the psu and mobo.

[DemiGod]

2 minutes ago, filpo said:

connect the 2+8 side to the psu where it say 'CPU'. Then connect one of the 8 pin cables (you should have two) to the motherboard, then rinse (obviously don't actually rinse) and repeat 

So one of the cable is just left hanging :? I mean When I connect one end to the PSU and another to CPU in motherboard, there are two end's so one is just left hanging ? 

[filpo]

2 minutes ago, DemiGod said:

So one of the cable is just left hanging :? I mean When I connect one end to the PSU and another to CPU in motherboard, there are two end's so one is just left hanging ? 

is this a pcie cable? Cuz it sounds like it 

[filpo]

3 minutes ago, DemiGod said:

That is the thing there is nothing I just took another look it's gigabyte 850UD.... No markings... At all. But Well I figured out it by taking a very good look at the pin themselves, but I am still not sure how connect it to the psu and mobo.

For the cpu cable there should only be one power connector per side. The motherboard side will have 8 pins so has to be an 8 pin and the psu side is different or its not

 

have you checked your manual? These normally have some documentation on how to put in the cables

[DemiGod]

1 minute ago, filpo said:

For the cpu cable there should only be one power connector per side. The motherboard side will have 8 pins so has to be an 8 pin and the psu side is different or its not

 

have you checked your manual? These normally have some documentation on how to put in the cables

Cha cha Yes I have the right cable, but I got the sides flipped as I understand the end with two cables is just an extension. For it to be longer. So I think I reversed the sides the two hanging cables go to psu and one side to cpu.

 

[DemiGod]

9 minutes ago, filpo said:

For the cpu cable there should only be one power connector per side. The motherboard side will have 8 pins so has to be an 8 pin and the psu side is different or its not

 

have you checked your manual? These normally have some documentation on how to put in the cables

this is from the manufacturers page:

[filpo]

1 minute ago, DemiGod said:

this is from the manufacturers page:

oh ok so it was just an extension then got it

 

So have you solved it then?

[DemiGod]

6 minutes ago, filpo said:

oh ok so it was just an extension then got it

 

So have you solved it then?

Almost. Still one small question remains, if my PSU has 2-3 Slots for CPU power why does it only have one cable. I still have some hope that I can just plug both of the cables to the cpu in the motherboard for 16 pin power. I know it probably is not how it works. SO I assume I need to go out and buy another cpu cable for my setup :? I mean 8 pins will probably be enough but, I will need to buy it if I ever want to upgrade, or overclock. And no markings on the cables is seriously stupid. I already jammed pcie cable into cpu slot, before realizing. I am glad I did not break anything

[filpo]

Just now, DemiGod said:

SO I assume I need to go out and buy another cpu cable for my setup :? I mean 8 pins will probably be enough but, I will need to buy it if I ever want to upgrade, or overclock. And no markings on the cables is seriously stupid. I already jammed pcie cable into cpu slot, before realizing. I am glad I did not break anything

you can go and buy it but make sure that its for your psu otherwise

 

KABOOM

 

Also yes you could do that, idk why gigabyte doesn'tship it with the cables

[filpo]

Just now, filpo said:

you can go and buy it but make sure that its for your psu otherwise

 

KABOOM

 

Also yes you could do that, idk why gigabyte doesn'tship it with the cables

 

Just now, DemiGod said:

if my PSU has 2-3 Slots for CPU power why does it only have one cable

those other two slots might be for pcie power (unless they're labeled otherwise)

[DemiGod]

9 minutes ago, filpo said:

 

those other two slots might be for pcie power (unless they're labeled otherwise)

Apparently there is no difference between cpu and pci-e cables so yeah. They are pci-e cables but also cpu cables. 

[filpo]

1 minute ago, DemiGod said:

Apparently there is no difference between cpu and pci-e cables so yeah. They are pci-e cables but also cpu cables. 

Oh ok alright. If you know which cables are which just put them in the corresponding ports

[DemiGod]

Just now, filpo said:

Oh ok alright. If you know which cables are which just put them in the corresponding ports

I did it's not the issue anymore. Well I guess the original question has been solved, so thank you for your answers and your time. But I will have to contact gigabyte support. 

[filpo]

1 minute ago, DemiGod said:

I did it's not the issue anymore. Well I guess the original question has been solved, so thank you for your answers and your time. But I will have to contact gigabyte support. 

oh ok sorry lost track a bit lol. Whats the problem now? 

[DemiGod]

6 minutes ago, filpo said:

oh ok sorry lost track a bit lol. Whats the problem now? 

That there is only one cable and I need two But it's not an issue for this topic, it's an issue for gigabyte support. 

[filpo]

Just now, DemiGod said:

That there is only one cable and I need two But it's not an issue for this topic, it's an issue for gigabyte support. 

ye alr. Should've been included in the box tho

[DemiGod]

16 minutes ago, filpo said:

ye alr. Should've been included in the box tho

Yeah I thought I misplaced it but it says in the box only one. 

[mariushm]

They use the same connector on the power supply side, because it's possible to do it. 

pci-e uses 3 12v wires and 5 ground wires.

cpu uses 4 12v wires and 4 ground wires. 

 

So the connector on the power supply has 4 12v pins, and 4 ground pins. 

The pci-e cable will connect the 5th ground wire with the 4th wire to one of the 4 pins and just won't connect anything to the 4th 12v pin. 

The cpu cable is straight forward, 4 12v wires go to 4 12v pins, 4 ground wires go to 4 ground pins. 

 

There is a difference between CPU (EPS) connector that plugs in motherboard, and the pci-e connector that plugs in video card.

One of them has the 12v wires on the side with the retaining clip , the other one has the 12v on the opposite side. 

 

 

In order for idiots to not plug them the wrong way or in the wrong place, the connectors are KEYED. If you look at the actual pins, you will see that the plastic has certain shape. Some pins in the connector on motherboard will be square, some will have a D shape.. if you try to plug it in the wrong place it will not fit, it won't go easily. 

This is how it looks on motherboard : 

 

and these are on the video card ... note that D shapes are in different locations, so you wouldn't be able to plug CPU connector into pci-e 8 pin connector. Pin 5 (bottom left) on connector would not go into the bottom right pci-e 5th pin hole, due to its shape... 

 

 

The CPU connector on the power supply cable may not match 100% when it comes to the keying, because it's slightly changed by the manufacturer from the standard so that someone can plug either of the 4 pin parts  (when the 8 pin is separated into 2  4 pin pieces) into a 4 pin header on the motherboard, if the motherboard has only a 4 pin cpu connector / header.

 

[DemiGod]

3 minutes ago, mariushm said:

They use the same connector on the power supply side, because it's possible to do it. 

pci-e uses 3 12v wires and 5 ground wires.

cpu uses 4 12v wires and 4 ground wires. 

 

So the connector on the power supply has 4 12v pins, and 4 ground pins. 

The pci-e cable will connect the 5th ground wire with the 4th wire to one of the 4 pins and just won't connect anything to the 4th 12v pin. 

The cpu cable is straight forward, 4 12v wires go to 4 12v pins, 4 ground wires go to 4 ground pins. 

 

There is a difference between CPU (EPS) connector that plugs in motherboard, and the pci-e connector that plugs in video card.

One of them has the 12v wires on the side with the retaining clip , the other one has the 12v on the opposite side. 

 

 

In order for idiots to not plug them the wrong way or in the wrong place, the connectors are KEYED. If you look at the actual pins, you will see that the plastic has certain shape. Some pins in the connector on motherboard will be square, some will have a D shape.. if you try to plug it in the wrong place it will not fit, it won't go easily. 

This is how it looks on motherboard : 

 

and these are on the video card ... note that D shapes are in different locations, so you wouldn't be able to plug CPU connector into pci-e 8 pin connector. Pin 5 (bottom left) on connector would not go into the bottom right pci-e 5th pin hole, due to its shape... 

 

 

The CPU connector on the power supply cable may not match 100% when it comes to the keying, because it's slightly changed by the manufacturer from the standard so that someone can plug either of the 4 pin parts  (when the 8 pin is separated into 2  4 pin pieces) into a 4 pin header on the motherboard, if the motherboard has only a 4 pin cpu connector / header.

 

Thanks that is exactly how I managed to separate them. By looking at the differences between squares and oval-squares. Thanks for the extensive answer. And if you are so knowledgeable could you also clarify, why my cpu cable, has two headers. Is it only for length ? And I leave one hanging after I insert one head ? (My mobo has slots for 2*8).

[mariushm]

Some motherboards have 2 8 pin headers (ex dual socket motherboards), very high end / heavy overclocking motherboards. 

 

2 cpu socket motherboards often used 2 8 pin connectors, one for each cpu socket,  even though individually each cpu may not use a lot of power. 

 

For multiple reasons, each connector is rated (and artificially limited by the EPS standard) for around 300 watts (4 pairs x 7A per pair x 12v = 336 watts)  but each cpu usually only consumed 100-150 watts, so it's safe and possible to feed two processors using a single cable coming from power supply. 

On the power supply end, in theory each pair of wires can carry more than 10A, but the actual pins in the connector are rated for minimum 9A (so you have at least 4 pairs x 9A x 12v = 432w)

 

Some psu manufacturers used one 8 pin CPU connector and the 2nd one on the cable would be split-able in two parts, for use with older motherboards that still used a 4 pin cpu header. This way, if your motherboard had a 8 pin header, you could plug the 8 pin connector that's closer to power supply on the cable and hide the 2nd connector behind the motherboard. 

 

 

 

[DemiGod]

18 minutes ago, mariushm said:

Some motherboards have 2 8 pin headers (ex dual socket motherboards), very high end / heavy overclocking motherboards. 

 

2 cpu socket motherboards often used 2 8 pin connectors, one for each cpu socket,  even though individually each cpu may not use a lot of power. 

 

For multiple reasons, each connector is rated (and artificially limited by the EPS standard) for around 300 watts (4 pairs x 7A per pair x 12v = 336 watts)  but each cpu usually only consumed 100-150 watts, so it's safe and possible to feed two processors using a single cable coming from power supply. 

On the power supply end, in theory each pair of wires can carry more than 10A, but the actual pins in the connector are rated for minimum 9A (so you have at least 4 pairs x 9A x 12v = 432w)

 

Some psu manufacturers used one 8 pin CPU connector and the 2nd one on the cable would be split-able in two parts, for use with older motherboards that still used a 4 pin cpu header. This way, if your motherboard had a 8 pin header, you could plug the 8 pin connector that's closer to power supply on the cable and hide the 2nd connector behind the motherboard. 

 

 

 

I understand this, but my situation is as follows. The cpu cable has 2*8 pins. On one end and 1*8 on another end. So I plugged 1*8 to my psu. And I am a little bit confused, what do I do with 2*8 end, do I plug only one 8 pin and leave another one dangling ? Or I plug both of them ? But logically speaking it would provide only 320W anyways. 

[mariushm]

You do whatever you want. 

Use only one 8 pin , or plug both 8 pin connectors if your motherboard has 2  8 pin headers. psu doesn't care, motherboard won't care.

 

If your motherboard has  only 1  8 header, then plug the one connector closest to the psu and leave the other one hanging, unused. 

 

on motherboards that have 2 8 pin header , ideally you use a second cable between psu and the 2nd header, because more wires means less losses, less heating in the wires, in theory it's better. The current is spread across more wires so it's better. 

But if you don't do serious overclocking, then it's not needed to plug stuff in the second 8 pin header.