I suddenly started to smell burning plastic and right away had a deep look at the PSU. 4090 side connector is absolutely fine (fortunately) but the PSU end actually fused together. I tried pulling them out using some pliers but no luck, I feel the plastic on the PSU will snap.
I am using the Corsair SF750 with a Corsair 12VHPWR cable with my Zotac 4090 for about 1 year now.
Others has mentioned that I haven't plugged it in well enough but clearly it is too well plugged in and now they're even bonded together.
I'm quite lost – How do I prevent this happening again when I go buy a new PSU and cable?
21 Comments
What the fuck? That’s really strange considering corsairs PCIe cables are rated for 300W each. ~~Should be RMA worthy since all parts are Corsair yeah?~~
Edit: probably can’t get an RMA on this. See other comments, as the PSU is not in spec to run a 4090.
isnt the 750w like 250w less than the recommended for that gpu?
https://www.corsair.com/uk/en/explorer/diy-builder/power-supply-units/what-psu-is-best-for-rtx-4090/
honestly id recommend getting a larger psu with more surface to dissipate heat, like thats not a poor quality PSU probably just run at high temps ALL the time trying to power a 4090
This isnt a 12VHPWR issue because the PSU side connection is not part of the ATX specification.
Its entirely Corsair’s responsibility to ensure the modular connectors can handle the power. Corsair only using 2 connectors on the PSU side instead of all 4 is their fault entirely.
Is it a dual 12v rail PSU?
pretty sure heat is the killer here.
there is no cable compatibility. the sf750 takes type 4 pcie cables. the corsair 12vhpwr cable is type 4.
the problem, is with the small form factor of the psu. corsair obviously had to cram a bunch of high voltage components into a tiny space, in comparison to its rm750 atx counterpart.
a regular rm750 is 150xmm x 86mm x 160mm. the sf750 is 100mm x 63mm x 125mm.
the sf750 is about 39% the size of the rm750. the sf750 is 787.5 cubic centimeters vs rm750 at 2064 cubic centimeters.
high voltage components are definitely going to be causing serious heat in something that small. especially if the psu is being run constantly above 80% of its total watt rating.
heat increases electrical resistance.
next time use a regular atx power supply to power a 4090
[https://www.corsair.com/us/en/s/psu-cable-compatibility](https://www.corsair.com/us/en/s/psu-cable-compatibility)
[https://www.corsair.com/us/en/p/pc-components-accessories/cp-8920284/600w-pcie-5-0-12vhpwr-type-4-psu-power-cable-cp-8920284](https://www.corsair.com/us/en/p/pc-components-accessories/cp-8920284/600w-pcie-5-0-12vhpwr-type-4-psu-power-cable-cp-8920284)
[https://www.corsair.com/us/en/p/psu/cp-9020195-na/rm-series-rm750-750-watt-80-plus-gold-certified-fully-modular-psu-cp-9020195-na#tab-techspecs](https://www.corsair.com/us/en/p/psu/cp-9020195-na/rm-series-rm750-750-watt-80-plus-gold-certified-fully-modular-psu-cp-9020195-na#tab-techspecs)
[https://www.corsair.com/us/en/p/psu/cp-9020186-na/sf-series-sf750-750-watt-80-plus-platinum-certified-high-performance-sfx-psu-cp-9020186-na#tab-techspecs](https://www.corsair.com/us/en/p/psu/cp-9020186-na/sf-series-sf750-750-watt-80-plus-platinum-certified-high-performance-sfx-psu-cp-9020186-na#tab-techspecs)
Why isn’t there a 3rd 8-pin cable connected?
750 is not good eough for 4090 + the cable shuold of had at lest 3 on that end ..
Corsairs 12VHPWR cable sucks. It wouldn’t even power my 4080 super. Had to use the octopus cable that came with the card. Now I’m glad I returned it.
The SF750 isnt spec’d for the 4090 anyways, your problem not us. The 4090 literally requires a 850w and everyone recommends a 1000w
I’d say the connectors on the PSU side are at fault here, the GPU is demanding more power through each connector than they’re designed for since it’s all just going through two (rather than four on the octopus for example). Everything on the cable side can handle it but that PSU is out of spec for a 4090.
I refuse to use a card with one of these cables. My 4070 provides what I want and only needs a single eight pin for 200 watt maximum power draw.
Yeah down vote all you want but it’s one power cable that’s consistently problematic.
Tis but a scratch!
Just not so modular anymore..
Crap I’ve got a zotac 4090 with the Corsair cable adaptor. Now I need to go look at mine. PS is a Corsair rm1000 gold but it’s an older one
Running a 4090 on a 750 is crazy lol
Even if that is technically out of spec, that PSU should just shut off, not fucking melt lmfao
is his PSU unfixable? should he buy a new one?
This is a user error now
> I’m quite lost – How do I prevent this happening again when I go buy a new PSU and cable?
Maybe do research next time?
The problem is not so much the power draw.
There were most likely loose contacts inside the connectors, that causes small sparks and carbon deposits on the surface of the metal connection, which leads to high resistance and to more heat.
Depending on the rest of your build, that PSU could be enough, but I’d suggest getting at least a 850W.
Unfortunately Corsair likely won’t back you up, but this comment section sure is full of the usual Reddit responses
“4090 needs 850” wrong, that’s the official psu recommendation so Nvidia can’t be sued if someone decides to use some crappy 80 plus psu, it only actually uses around 450w max
“It’s the adapter, pcie is only specced for 150w” this still plagues the internet unfortunately. First of all, the official Corsair 600w 12vhpwr adapter is 2x 8 pin, and this psu comes with 1-2x pin daisy chains, I’ve been using a 340w 3080 on one of those for over a year. Technically a single 8 pin could pull 320w and be in spec considering gauge
This was most likely improper contact or a faulty cable. Yes it’s not officially compatible, but that changes less than people think, considering the hundreds of users running 4090 on it
Edit: Head of PSU RnD at corsair seems to believe the most likely cause was the connector wasn’t plugged in properly
You should check if you can claim warranty on that.