Question Issue with new graphics card power in relation to mobo requirements and case

[punkncat]

My case is a Lian Li O11D Mini. It only takes SFX power supplies.

The motherboard in this is a MSI Z590 Unify (full ATX)

Power supply is a Corsair SF750 Platinum.

Graphics card is the Sapphire RX7800XT (2x8 pin power)


The issue:

The motherboard in this build has a 6 pin connector for PCI supplemental power at the bottom. Connecting this cable to the motherboard eliminates the proper length of the other connector (there are 2 6x2 connectors on each of the PCI cables) to reach the end of the graphics card to plug in. Even with the other cable I had to do a bit of rearrangement to get even one of the cables there. I am currently using the one cable plus daisy chained plug to power the graphics card, which is not ideal.

I cannot find anything in the manual or online to tell me if this supplemental cable has to be hooked up on the motherboard, and I have not tried without it out of concern. It is my understanding that the PCI slot can provide 75W. I don't know if the other power cable to the motherboard is increasing that or not.

I am hoping not to have to purchase an entire cable extension kit just to deal with this issue if I even need to. When I search for 8 pin extensions all I am getting are sketchy KnM cables. Is it possible to purchase just a 2x8 pin PCI power extension cable for less than the whole kit?
Reference- Antec has a whole kit for $20

 

[Colif]

There are three sources:

1. The PCI Express slot of the motherboard can provide up to 75 watts to the graphics card.
2. 6-pin power connector can provide up to 75 watts.
3. 8-pin power connector can provide up to 150 watts.

The maximum power consumption of the connectors. - GIGABYTE Global

GIGABYTE The maximum power consumption of the connectors. service, ensuring you have the best experience when using GIGABYTE products and services.

www.gigabyte.com

I don't think you can push more power through the slot. I expect cards are expecting a certain amount there... it could be troublesome.

supplemental cable. Does the connector have a label?
In manual (page 8) it shows where to put power... CPU_PWR1, CPU_PWR2, PCIE_PWR1 (6 pin)

https://download.msi.com/archive/mnu_exe/mb/E7D38v1.0.pdf

PCIE_PWR1:

It simply provides extra power to the PCI lanes to improve stability. If you're only running a single GPU, you don't need to worry about it.

link
You don't need the cable attached to mb. You sound like you have the cables you need now. just use the 2 pcie connectors on 1 cable on GPU if you need two. I doubt the card will pull that much, you can probably run off one cable if you wanted to. Both 8 pin connectors on the wire push 150.

Unlike my 7900xt which is better suited with 2 cables.

https://res.cloudinary.com/corsair-pwa/image/upload/corsairmedia/sys_master/productcontent/SF_PLATINUM_User_Manual.pdf

my RMx 1kw has 4 of the 6 + 2 pcie cables. Overkill really.

Do corsair sell extensions? I wouldn't mix makes as the color of wires could be different. You can break things.

 

[punkncat]

I went ahead and contacted MSI support. The connector at the bottom of the board is there for "having multiple high power GPU".
Never mind that there is only one slot on this board...They did not add that it actually increased the power on the slot, so really not even sure why it is there if that is the only use case. This board does have quite a few M.2 slots down there, so who knows.
They did tell me that the motherboard can be powered without it, so if I can get it to reach I may try to reroute it.

Corsair has a kit available, but it is darned high for what it is. I was considering trying to find something along the lines of "Cable Mod" or other reputable company making the universal side for the connector hardware side. The issue being that I cannot seem to find the 2x8 cable outside of the whole kit that I don't really want. Price wise I might just go that route.

 

[Colif]

Never mind that there is only one slot on this board...

they might be foreseeing a dual chip GPU... its been done before.

It sounds like its for crossfire, and makes sure both GPU get the power they expect and one isn't hogging it. Stll pointless on your board... what were they smoking that day.

Can't you use one 6+2 cable (since both cables have 2 connectors) or it still doesn't reach GPU?

 

[punkncat]

they might be foreseeing a dual chip GPU... its been done before.

It sounds like its for crossfire, and makes sure both GPU get the power they expect and one isn't hogging it. Stll pointless on your board... what were they smoking that day.

Can't you use one 6+2 cable (since both cables have 2 connectors) or it still doesn't reach GPU?

The issue on the stock cabling, aside for having one plugged in on the bottom of the mobo has to do with length and the PSU location for the case. It is in the upper back right looking from the front. The only way I could get one cable to reach out there was to plug it in the bottom most right spot on the PSU and out along the 'end' of the card. Barely got both plugged in. Even with the other cable unplugged, and other spot and it's either too short, or I have that unused connector (of the daisy chain) hanging in the breeze while using the additional connector for that extra inch.

I am going to shoot Corsair a message and see if they have something I can get from them directly. I don't mind the cabling of this PSU and don't really want an entire extension kit to shove in the back panel.

Thank you for your suggestions.

 

[Colif]

PSU in 2nd chamber? i hadn't looked at that case before.

what layout you using as "end of card" confuses me as I can see PSU goes behind MB tray.

Lian Li O11 Dynamic Mini chassis review (Page 10)

This time, we’re checking out the Lian Li O11D Mini, a smaller version of the well-known O11D series. We reviewed the regular version over 2.5 years ago, and it earned our “Recommended” award. This time, it’s a smaller case, but still a very spacious one. It looks like an ITX/mATX chassis, but...

www.guru3d.com

I stop helping if you waiting on Corsair

 

[punkncat]

PSU in 2nd chamber? i hadn't looked at that case before.

what layout you using as "end of card" confuses me as I can see PSU goes behind MB tray.


I stop helping if you waiting on Corsair

In the link above, it shows how the PSU is in the upper back right of the case, behind the motherboard tray. The power connectors are on the outer edge all the way to the end away from outputs. The connectors for the modular cables are just barely not long enough for me to get to the GPU due to the nature of wire routing and a full sized ATX board.

Corsair does sell a kit that are individually sleeved 8 pin connectors without the daisy chain aspect , and are just over 2' long which will hopefully give me enough to reach. These replace the other (type 4) stock cables. They are $30 for a pair, so not the best deal around, but at least are official for and warrantied for Corsair PSU.

 

[Colif]

i guess sfx psu not designed to accommodate ATX boards.

 

[punkncat]

i guess sfx psu not designed to accommodate ATX boards.

I have read that a fairly common complaint with several of the SFX is having short cables. This works out well when you are trying to cram things into an M-ITX case...not so much when trying to work with an otherwise full size rig.

 

[Colif]

it makes sense as its designed for smaller cases and then you would get complaints about cables being too long.

Only real answer is extra cables. Now whether those should be free and in box, or just something you order, is a good question. I feel it probably come down to what size most cases in that format are sized as. Pattern seems to be for smaller cases so long cables is just more to hide in less space.

So making the few people with bigger boards pay more is likely a cheaper option than extra cables most won't use.