Corsair 750Hx: Difference between 6+2 and 8pin cables?

[BigBossBanzai]

Hi,

 

Sorry for the probably obvious question, but I get nervous with PSU stuff:

I just got a Corsair Hx750. It has 4x8pin sockets, but only came with 2 PCI-E labelled (6+2pin) cables, and 2 CPU (8pin) labelled cables. Am I safe in using the second CPU cable if I end up going with a 3x8pin GPU? There is no functional difference between the cables beyond one being split 6/2, is there?

About the sockets, do the cables mean 2 of the 8pin sockets on the PSU are meant for CPU? The sockets are kind of labelled weirdly that I cant tell which is which, is there a difference in the sockets?

 

See attachment for how it looks.

 

Thanks for any help!

 

 

[Alex Atkin UK]

26 minutes ago, BigBossBanzai said:

Hi,

 

Sorry for the probably obvious question, but I get nervous with PSU stuff:

I just got a Corsair Hx750. It has 4x8pin sockets, but only came with 2 PCI-E labelled (6+2pin) cables, and 2 CPU (8pin) labelled cables. Am I safe in using the second CPU cable if I end up going with a 3x8pin GPU? There is no functional difference between the cables beyond one being split 6/2, is there?

About the sockets, do the cables mean 2 of the 8pin sockets on the PSU are meant for CPU? The sockets are kind of labelled weirdly that I cant tell which is which, is there a difference in the sockets?

 

See attachment for how it looks.

 

Thanks for any help!

 

No, the connectors are different.

I'm fairly sure no GPU needs more than 2x8 pin though.

[Haro]

35 minutes ago, BigBossBanzai said:

. Am I safe in using the second CPU cable if I end up going with a 3x8pin GPU?

No, they have completely different pin layout. 

[Mondas42]

9 minutes ago, Alex Atkin UK said:

No, the connectors are different.

I'm fairly sure no GPU needs more than 2x8 pin though.

Except for the new high end ASUS 3080,3090. These need three 8 pin connectors but plenty of others only need 2x 8 pins.

[Kilrah]

You cannot use the CPU cable to connect to a GPU, won't fit and is wired differently. But you can get more 6+2s that match your PSU and use that.

[BigBossBanzai]

Thank you for the replies. I didn't want to rip everything apart again to check if it could even fit, so thank you for saving me the time and frustration.

Turns out I missed that both PCI-E cables split into two 6+2 connectors each, so the 2 cables should be enough. Or should I not use one cable to fill two slots on the gpu?

[Ankerson]

7 hours ago, BigBossBanzai said:

Thank you for the replies. I didn't want to rip everything apart again to check if it could even fit, so thank you for saving me the time and frustration.

Turns out I missed that both PCI-E cables split into two 6+2 connectors each, so the 2 cables should be enough. Or should I not use one cable to fill two slots on the gpu?

 

Use both cables.

[BigBossBanzai]

5 hours ago, Ankerson said:

 

Use both cables.

Yeah, obviously. But the question is if I would be fine using two cables to fill 3 8pin slots on a GPU. 1 cable gets two 6+2 slots, another gets a slot on its own.

[Ankerson]

19 minutes ago, BigBossBanzai said:

Yeah, obviously. But the question is if I would be fine using two cables to fill 3 8pin slots on a GPU. 1 cable gets two 6+2 slots, another gets a slot on its own.

 

NO...

 

You would need 3 cables one for each 8 Pin.

 

Although with the HX 750W I would try it as you are thinking.... That's a much better PSU than most.... Switch it to Multi-Rail and go for it.

 

The HX 850W would have had enough PCIe cables that you could have used 3 separate cables for the 3x 8 pin.

[Alex Atkin UK]

15 hours ago, Mondas42 said:

Except for the new high end ASUS 3080,3090. These need three 8 pin connectors but plenty of others only need 2x 8 pins.

They must be seriously overclocked models to do that.  The reference cards use 2x8pin adapters so the cards can pull up to 375W (2x 150W 8pin + 75W PCIe slot), stock at 320W.

[Ankerson]

6 minutes ago, Alex Atkin UK said:

They must be seriously overclocked models to do that.  The reference cards use 2x8pin adapters so the cards can pull up to 375W (2x 150W 8pin + 75W PCIe slot), stock at 320W.

 

NO, they are using the 12 Pin to connects into the GPU and it can provide over 500W easily and up to 648W.

 

The PSUs will provide the power needed by the adaptor from the 2x 8 pin connection into the adaptor....

 

So there is no 375W limit....

 

 

[Alex Atkin UK]

3 minutes ago, Ankerson said:

 

NO, they are using the 12 Pin to connects into the GPU and it can provide over 500W easily and up to 648W.

 

 

Yes and it comes with a dual 8 pin to 12 pin adapter cable.

 

[Ankerson]

3 minutes ago, Alex Atkin UK said:

Yes and it comes with a dual 8 pin to 12 pin adapter cable.

 

With no 375W total power limit...

 

That 150+150 limit... Is gone...

[Alex Atkin UK]

Just now, Ankerson said:

 

With no 375W total power limit...

Says who?  All NVIDIA cards have some sort of current limit, them capping it at 375W overclocked and 320W stock would seem a no brainer.

[Ankerson]

3 minutes ago, Alex Atkin UK said:

Says who?  All NVIDIA cards have some sort of current limit, them capping it at 375W overclocked and 320W stock would seem a no brainer.

 

Dream on... 

 

Those days are over.....

 

Wait until the reviews come out etc.... 

 

I am expecting to see well over 400W power draw.....

[Alex Atkin UK]

3 minutes ago, Ankerson said:

 

Dream on... 

 

Those days are over.....

 

Wait until the reviews come out etc.... 

 

I am expecting to see well over 400W power draw.....

Well we should know soon, but all the channels I've been following think that will still need shunt mods to bypass the BIOS limiter.

[Ankerson]

6 minutes ago, Alex Atkin UK said:

Well we should know soon, but all the channels I've been following think that will still need shunt mods to bypass the BIOS limiter.

 

The BIOS limiter will just be HIGHER than 400W..... They will just open it up so it can draw the power needed....

 

Really the only thing that limits the 2080Ti to 375W is the BIOS limiter, the power connection 2x 8 pin can actually handle more than that, a lot more...

 

The PCB can handle a lot more power....

[Alex Atkin UK]

1 minute ago, Ankerson said:

 

The BIOS limiter will just be HIGHER than 400W.....

 

Really the only thing that limits the 2080Ti to 375W is the BIOS limiter, the power connection 2x 8 pin can actually handle more than that, a lot more...

Well it would be a nice surprise, even though my PSU is only 650W so its only going to cope if I keep it stock.

Yeah I know they recommend 750W but I can see from my current consumption it will handle it fine as its not even hitting 550W from the wall with CPU and GPU maxed.  That 650W rating is OUTPUT not input, you always pull more from the wall than you put out.

[Ankerson]

6 minutes ago, Alex Atkin UK said:

Well it would be a nice surprise, even though my PSU is only 650W so its only going to cope if I keep it stock.

Yeah I know they recommend 750W but I can see from my current consumption it will handle it fine as its not even hitting 550W from the wall with CPU and GPU maxed.  That 650W rating is OUTPUT not input, you always pull more from the wall than you put out.

 

That 750W PSU recommendation and then Seasonic saying 850W is a real hint of what is coming....

 

I wouldn't be surprised to see 420W from the 3080 and 450W from the 3090... And over 300W from the 3070....

[Alex Atkin UK]

58 minutes ago, Ankerson said:

 

That 750W PSU recommendation and then Seasonic saying 850W is a real hint of what is coming....

 

I wouldn't be surprised to see 420W from the 3080 and 450W from the 3090... And over 300W from the 3070....

Officially you're only supposed to pull 150W per 8 pin, not sure how the sockets on modular PSUs work, if they can carry more than that safely.

[Ankerson]

5 minutes ago, Alex Atkin UK said:

Officially you're only supposed to pull 150W per 8 pin, not sure how the sockets on modular PSUs work, if they can carry more than that safely.

 

Yes, they can and do provide more than 150W... From the PSU if needed.. That's why wire gauge is so important....

 

That's why some people can get away with using the daisy chain cable for the GPU that pulls over 150W from the PSU.....

 

 

[Alex Atkin UK]

3 minutes ago, Ankerson said:

 

Yes, they can and do provide more than 150W... From the PSU if needed.. That's why wire gauge is so important....

But also why NVIDIA changed the socket, I'm not sure what the PCIe socket is meant to do - around 225W (remember seeing something mentioned)?

[Ankerson]

1 minute ago, Alex Atkin UK said:

But also why NVIDIA changed the socket, I'm not sure what the PCIe socket is meant to do - around 225W (remember seeing something mentioned)?

 

 

[Kilrah]

6 hours ago, Ankerson said:

 

NO, they are using the 12 Pin to connects into the GPU and it can provide over 500W easily and up to 648W.

 

The PSUs will provide the power needed by the adaptor from the 2x 8 pin connection into the adaptor....

 

So there is no 375W limit....

 

 

There is, since you're not supposed to pull more than 150W from an 8-pin cable.

Doesn't matter if the 12pin is rated 500W if you're using an adapter that pulls from 2 8-pins from which no more than 150W should be taken on each. 

 

If you assume "well there's margin" then there's no difference at all between having the 12pin on the card or not.

[Ankerson]

41 minutes ago, Kilrah said:

There is, since you're not supposed to pull more than 150W from an 8-pin cable.

Doesn't matter if the 12pin is rated 500W if you're using an adapter that pulls from 2 8-pins from which no more than 150W should be taken on each. 

 

If you assume "well there's margin" then there's no difference at all between having the 12pin on the card or not.

 

You are dreaming.... 

 

The PSU doesn't know or care how much the limits are.

 

It supplies the wattage needed....

 

Which is why people can use those daisy chained cables (2x 8 pin on the GPU End) to supply well over that 150W per 8 Pin..... That's from 1x 8 Pin on the PSU end.....

 

The power isn't capped off on the PSU end at 150W per 8 Pin.... As long as the wire gauge is big enough to handle the wattage needed it can indeed supply over 250w per 8 Pin on the PSU side....

 

Take my PSU for example, HX 850W in Multi-Rail mode can put out up to 40A or 480W per rail and all of the 12V+ connections are on separate rails...... Or in single rail mode it could supply the full 850W through one 8 pin on the PSU side,,,, Taking into count the wire gauge and if the connectors didn't melt with the full 70.8A.... They likely would melt so that's an extreme unrealistic example....

 

 

The power limits are on the component side as in this case the GPU....

 

So with the 12 Pin they could raise the power limit to 500W if they wanted to.... The PSU would supply the wattage over the 2x 8 pin on the PSU side, or 250W per 8 Pin.... On the PSU end to the 12 Pin connection on the GPU end. That we already know can happen as a single 8 Pin on the PSU end can and will and does supply 250W to a GPU through the Daisy Chained PCIe cable.... These are the facts and they are not disputable....