Where do I connect?

[Wizzardoz]

It is a few years since I last built a PC. Am puzzled with the PSU and Asus Crosshair VII Hero Motherboard connections to Corsair RM750i PSU. I can see where the 24pin connection goes from MB to PSU but not sure about the 8 pin / 4pin connections on the MB. Using Ryzen 2700X CPU, do I need the 8+4 connections and where does the other end go on the PSU please?

[Nerdom]

The 4/8 EPS power is labeled as 4+4CPU on the PSU. Any of those 3 plugs should work for an EPS connection, but I’ve never worked with a RM series before. The manual probably has your info.

 

and yes you need the connections.

[seon123]

You don't need more than an 8 pin for any mainstream platform CPU. It's just marketing, and as useless as RGB. 

You can plug in CPU or PCIe power cables into any of the 8 pin plugs. 

[Constantin]

This PSU only support one EPS connector, the motherboard has 2

[PopsicleHustler]

You only have you use a single 8pin connector for the CPU. Cables that were included with the PSU should have markings on them like CPU and PCI-E for CPU and GPU respectively.

 

CPU connectors are 4+4, GPU connectors are 6+2 in case markings are missing.

[Guest]

21 hours ago, Constantin said:

This PSU only support one EPS connector, the motherboard has 2

No.  This PSU supports up to three.  It only comes with one cable, though.

 

OP only needs one for his CPU. 

 

The 4+4 that plugs into the motherboard will plug into one of the ports labeled 4+4 on the PSU.

 

[Constantin]

4 minutes ago, jonnyGURU said:

No.  This PSU supports up to three.  It only comes with one cable, though.

 

OP only needs one for his CPU. 

 

The 4+4 that plugs into the motherboard will plug into one of the ports labeled 4+4 on the PSU.

 

It doesn't go like this, there are 3 4+4 connectors, but only one support the CPU 

[Guest]

1 minute ago, Constantin said:

It doesn't go like this, there are 3 4+4 connectors, but only one support the CPU 

You are very incorrect good sir.  Completely wrong and should not be advising others.

 

All three of those 8-pin ports are the same.  Any one of those three can be used for EPS12V or PCIe.  All three can be used for EPS12V or all three can be used for PCIe.  All three have the same pin-out.

 

[Constantin]

4 minutes ago, jonnyGURU said:

You are very incorrect good sir.  Completely wrong and should not be advising others.

 

All three of those 8-pin ports are the same.  Any one of those three can be used for EPS12V or PCIe.  All three can be used for EPS12V or all three can be used for PCIe.  All three have the same pin-out.

 

I have been digging this very deep, as i have a mobo that needs 2 cpu connectors and out off those of the PSU the manufacturer says how many are for the CPU!!!!

As i have a PSU with 3 4+4 and only one works.

I have tried this with my won hands and eyes!!!

It's 2019 Google a bit before offending people like that!!!!

[Stefan Payne]

11 minutes ago, Constantin said:

It doesn't go like this, there are 3 4+4 connectors, but only one support the CPU 

How did you come up with that?
The label on the PSU is clear that that is PCIe/CPU

And the PSU doesn't care what you plug in...

[Stefan Payne]

Just now, Constantin said:

I have been digging this very deep, as i have a mobo that needs 2 cpu connectors and out off those of the PSU the manufacturer says how many are for the CPU!!!!

As i have a PSU with 3 4+4 and only one works.

I have tried this with my won hands and eyes!!!

It's 2019 Google a bit before offending people like that!!!!

You tell a Corsair Product Manager how his PSU is supposed to work???
You see the Problem here, do you??

As stated, the 8pin connectors are all the same on the PSU side. What you plug in there is not relevant for anyone. PSU especially....

 

So you're wrong. Simple as that.

[Constantin]

4 minutes ago, Stefan Payne said:

You tell a Corsair Product Manager how his PSU is supposed to work???
You see the Problem here, do you??

As stated, the 8pin connectors are all the same on the PSU side. What you plug in there is not relevant for anyone. PSU especially....

 

So you're wrong. Simple as that.

come and say that to my PSU, as i connected the second one and the system wont boot!

Edit: the cable wasn't included, i bought a new one

[Stefan Payne]

Just now, Constantin said:

come and say that to my PSU, as i connected the second one and the system wont boot!

Where did you get the second one??
Same Pinout?

[Constantin]

Just now, Stefan Payne said:

Where did you get the second one??
Same Pinout?

Yes

[Guest]

4 minutes ago, Constantin said:

come and say that to my PSU, as i connected the second one and the system wont boot!

Edit: the cable wasn't included, i bought a new one

No.  Then the second cable is the wrong pinout.

 

You bought the wrong cable.  That's why it doesn't work.  It's not because the PSU can't support two EPS12V cables.

 

Does the cable you bought say "type 3" or "type 4" where it plugs into the PSU?

[Constantin]

Just now, jonnyGURU said:

where it plugs into the PSU?

There where it says 4+4

[Guest]

45 minutes ago, Constantin said:

There where it says 4+4

That's an incomplete sentence and doesn't answer the question.

 

Was the cable specifically produced for use with Corsair PSUs.

 

Pin out is the same where it plugs into the motherboard, sure.  But the pin out where it plugs into the PSU is different depending on brand of PSU.

 

A Corsair PSU cable will say "type 3" or "type 4" where it plugs into the power supply.

[Corsair Nick]

@Constantin - Feel free to post some pics of the cable you purchased for your second EPS connection.  Clear shots of both connectors will help shed some light on what could be the issue.

[Constantin]

30 minutes ago, Corsair Nick said:

@Constantin - Feel free to post some pics of the cable you purchased for your second EPS connection.  Clear shots of both connectors will help shed some light on what could be the issue.

The motherboard has 1x8 pin that is connected and 1x4 pin, the cable in the pictures that i wanted to use

[Constantin]

@seon123 ?

[Guest]

1 minute ago, Constantin said:

The motherboard has 1x8 pin that is connected and 1x4 pin, the cable in the pictures that i wanted to use

Yeah... See... That's completely wrong.  That's why it doesn't work.

 

You're assuming the pinout at the PSU and the pinout at the motherboard is the same (eg "one to one").  It is not.  The connector that goes into the PSU is not the same as the connection on the motherboard.  

 

See, the pin out at the PSU is this:

 

Lock tab

GD GD GD GD 

12v 12v 12v 12v

 

The pinout on the motherboard is this:

 

Lock tab

12v 12v 12v 12v

GD GD GD GD

 

You are literally shorting +12V to ground by NOT using a Corsair cable.  You have to have a Corsair cable to go from the PSU to the motherboard. Not some run of the mill 8-pin to 4-pin adapter.

 

[Constantin]

5 minutes ago, jonnyGURU said:

Yeah... See... That's completely wrong.  That's why it doesn't work.

 

You're assuming the pinout at the PSU and the pinout at the motherboard is the same (eg "one to one").  It is not.  The connector that goes into the PSU is not the same as the connection on the motherboard.  

 

See, the pin out at the PSU is this:

 

Lock tab

GD GD GD GD 

12v 12v 12v 12v

 

The pinout on the motherboard is this:

 

Lock tab

12v 12v 12v 12v

GD GD GD GD

 

You are literally shorting +12V to ground by NOT using a Corsair cable.  You have to have a Corsair cable to go from the PSU to the motherboard. Not some run of the mill 8-pin to 4-pin adapter.

I have checked the +/- from the manual of the motherboard and the PSU and they correspond.

What are you saying?

[Ankerson]

You have to get the CPU power cable from Corsair.

 

I am sure if you call them they can send you one.

[Guest]

6 minutes ago, Constantin said:

I have checked the +/- from the manual of the motherboard and the PSU and they correspond.

What are you saying?

No, they do not.  I don't know how you "checked it", but the polarity of the pins on the power supply is completely opposite of the pins on the motherboard.

 

You accused me of not using Google... use Google yourself.  Search for something like "Corsair pinout".  You'll see that the polarity of the pins on the PSU are reversed from an EPS12V/ATX12V power connector.  Therefore, you cannot just take a standard 8-pin to 4-pin adapter and plug it directly into the PSU.  You have to have a CORSAIR COMPATIBLE CABLE plugged into the PSU FIRST to REVERSE that pinout BEFORE you can use an adapter and/or plug it into the motherboard.

 

[Constantin]

3 minutes ago, jonnyGURU said:

No, they do not.  I don't know how you "checked it", but the polarity of the pins on the power supply is completely opposite of the pins on the motherboard.

 

You accused me of not using Google... use Google yourself.  Search for something like "Corsair pinout".  You'll see that the polarity of the pins on the PSU are reversed from an EPS12V/ATX12V power connector.  Therefore, you cannot just take a standard 8-pin to 4-pin adapter and plug it directly into the PSU.  You have to have a CORSAIR COMPATIBLE CABLE plugged into the PSU FIRST to REVERSE that pinout BEFORE you can use an adapter and/or plug it into the motherboard.

 

You are correct, the pinout from the PSU is inverted..

Sorry for the long trouble!