850X and 3 PCIe EVGA 3080Ti but only 2 cables help

[GrampaBob69]

Hi I just bought this expensive 850X to power my new EVGA 3080Ti which has 3 PCIe but I only see 2 cables with this PSU for PCIe unless I have missed something here.  How do I tackle this?  Daisy chaining is not good.  Thanks for the help.

[Oldman61]

I got the exact same situation/question.  I have 3 CPU cables (8pin) and 2 PCIe (6-pin+2) cables...what to do?  As far as I can tell I only need one CPU power cable (8-pin).  Do I use one of the CPU (8-pin) cables, or send off for third PCIe (6-pin+2) cable?

Oldman61

 

[GrampaBob69]

I didn't bother waiting for an answer because it's probably obvious.  I ordered a 3rd PCIe cable from the CableMod store on Amazon.  The product description states it's for the Corsair RMx units.  A few threads on google pointed me there.  I'm sure it will be fine.  Turns out the 1000w version of the RMx comes with 3 PCIe cables by default.  Yes, I'd rather pay a few extra bucks initially to have it come with the 850 PSU by default since GPU's like ours need that 3rd cable yet can make use of the less than 1000w boxes.  In the meantime until it's delivered, I read to use the daisy chain in position 2 & 3 to make due, although not optimal, because slot 3 uses less power.  Lot's of people do say it's fine to daisy chain permanently btw.  I'm just choosing to not go the route since the stuff is expensive to risk damage.

I also ordered a GPU sag pole since this card is much wider than my old card.  I had a UpHere bracket to help the weight distribution on the old card, but but now this bracket extends across the fan area too close now.

Edited August 21, 2022 by GrampaBob69

[LeDoyen]

@Oldman61 the CPU and PCIE are keyed differently so they are not interchangeable, and the pinout is also different. Using one in place of the other with some.. mechanical persuasion, will lead to the PSU going in short circuit protection. You should get an additional PCIE cable 🙂

@GrampaBob69 Corsair PSUs (except some rare models like the AX1200 and old AX) use type 3 and type 4 cables. The only difference between the two types is the motherblard 24 pin cable.

All others, PCIE included are identical.

So if your cablemod cable is for RMx, it will work.

RMi, RMx use type 4, RM uses type 3, but the PCIE cable pinout is the same between the two types.

Have a look there 🙂 https://www.corsair.com/us/en/psu-cable-compatibility

[GrampaBob69]

5 minutes ago, LeDoyen said:

@Oldman61 the CPU and PCIE are keyed differently so they are not interchangeable, and the pinout is also different. Using one in place of the other with some.. mechanical persuasion, will lead to the PSU going in short circuit protection. You should get an additional PCIE cable 🙂

@GrampaBob69 Corsair PSUs (except some rare models like the AX1200 and old AX) use type 3 and type 4 cables. The only difference between the two types is the motherblard 24 pin cable.

All others, PCIE included are identical.

So if your cablemod cable is for RMx, it will work.

RMi, RMx use type 4, RM uses type 3, but the PCIE cable pinout is the same between the two types.

Have a look there 🙂 https://www.corsair.com/us/en/psu-cable-compatibility

Thanks for the clarification and that's a great reference table (might take a few glaces to digest it though).  Doh I have a few previous EVGA PSU units....maybe I can get their PCIe cables to work with duct tape and some modification?  eek!

[LeDoyen]

eeeh.. given the price of a PCIE cable i wouldn't risk frying expensive components with pinout errors to save pennies ^^'