Will my two 2x Molex to 8 pin work for my 3070 Ti?

[PremierBromanov]

Hello, 

Not super new to PC building, but certainly treading new waters here. I've been using A Corsair HX750 to power my rig for the last 5-7 years (who can remember). Previously, this was all good for powering a GTX 960, a 1600x, and a mobo that fits. 
 

I've never had to worry too much about how much power needs to go into my GPU, and the last time I messed with it was when the 960 was not new. Currently, my PSU supplies my 960 with a molex and a 2x Molex to 8pin and 2x molex to 6 pin adapter. Imagine my shock when I was 2 pins short on upgrading to the 3070 Ti. It's 750w so I'm hoping it will suffice.

I've been doing a bit of research in This thread and a bit on the stickied posts, but I'm unclear if I NEED to replace my PSU or if my 2x Molex to 8 pin adapters will suffice. To my understanding, there's basically no room for error here, I need all 300 watts just about, so any connection supplying only 75 watts will not work. 

So I guess my question is, can a single molex cable with 4 ports supply enough power to my GPU via two 2x-molex-to-8-pin adapters? Or, do I need to just buy a whole new PSU? Or, is there a good place to look for cable kits for my PSU? Im wary of 2nd hand sellers since, as far as I understand it, using some cables not designed for the PSU can be a hazard. 

For posterity, Here's my current build (and incoming change)

AMD 5600x CPU
GTX 960 being replaced with RTX 3070 Ti
16 GB ram
Gigabyte x570 Aorus Elite mobo 

A couple of HDDs and an m.2 SSD

Windows 10 

 

[Skiiwee29]

You should NEVER use adapters to adapt power for anything, let alone a high end graphics card. If your PSU does not have the proper connectors you need, then your best, and honestly only option should be to buy a proper PSU that will provide you the wattage and connection points you require. 

[The_russian]

Please just get a power supply with the proper PCIe power connectors, of all things to cheap out on that is a terrible one. 

17 minutes ago, PremierBromanov said:

as far as I understand it, using some cables not designed for the PSU can be a hazard.

You mean just like using cable and connectors not meant for high power draw can be a hazard?

 

I recommend watching this video:

 

 

 

Edit: If you linked the correct model of your power supply you should have gotten a total of 4 6+2 pin PCIe power connectors. Did you lose those cables?

Edited June 15, 2021 by The_russian

[Darkwing Drex]

Your PSU should have some 4x4 power cables included. Those will fit onto the 12 pin adapter that comes with the 3070 TI. If you dont have the cables or they dont fit, just replace the PSU with a modular one.

[PremierBromanov]

4 minutes ago, Darkwing Drex said:

Your PSU should have some 4x4 power cables included. Those will fit onto the 12 pin adapter that comes with the 3070 TI. If you dont have the cables or they dont fit, just replace the PSU with a modular one.

unless im mistaken my evga 3070ti didnt come with any cables to speak of.

The PSU cables are long gone, not sure where they went or are. 

[Skiiwee29]

4 minutes ago, PremierBromanov said:

unless im mistaken my evga 3070ti didnt come with any cables to speak of.

The PSU cables are long gone, not sure where they went or are. 

You said you have an HX750 right? You can order replacement kits for them direct from Corsair. However, looking over everything, that PSU is ancient, and likely out of warranty. I would replace it anyways and not worry/bother with replacement cables. 

[Spotty]

30 minutes ago, PremierBromanov said:

Not super new to PC building, but certainly treading new waters here. I've been using A Corsair HX750 to power my rig for the last 5-7 years (who can remember).

That's quite an old power supply. I bought the same model 12 years ago and used it until I bought a 1080ti a few years ago and replaced it for something newer (RM750x). Some good news is that it happens to use the same pinout for PCIe cables as Type 3/Type 4 used on the newer power supplies (I think, I would need to get my old unit out of storage and test it to double check), so it is possible to find replacement cables for it even after over a decade. However, I would recommend replacing the PSU with something newer. Especially if you're going to be using it with a brand new, very high end, very power demanding graphics card that is known to have power draw spikes.

 

42 minutes ago, PremierBromanov said:

I've never had to worry too much about how much power needs to go into my GPU, and the last time I messed with it was when the 960 was not new. Currently, my PSU supplies my 960 with a molex and a 2x Molex to 8pin and 2x molex to 6 pin adapter. Imagine my shock when I was 2 pins short on upgrading to the 3070 Ti. It's 750w so I'm hoping it will suffice.

I've been doing a bit of research in This thread and a bit on the stickied posts, but I'm unclear if I NEED to replace my PSU or if my 2x Molex to 8 pin adapters will suffice. To my understanding, there's basically no room for error here, I need all 300 watts just about, so any connection supplying only 75 watts will not work. 

So I guess my question is, can a single molex cable with 4 ports supply enough power to my GPU via two 2x-molex-to-8-pin adapters? Or, do I need to just buy a whole new PSU? Or, is there a good place to look for cable kits for my PSU? Im wary of 2nd hand sellers since, as far as I understand it, using some cables not designed for the PSU can be a hazard. 

Do not use adapter power cables.

The GTX 960 only draws about 125W which is probably why you've been lucky so far and gotten away with using molex adapter cables. The RTX 3070 Ti can draw more than twice as much power with 300W at stock on the FE card, with overclocked or board partner factory OC cards coming in at 325W+.

[PremierBromanov]

Thanks for the advice, it does seem wise to upgrade to a new PSU if Im going to upgrade literally every other part of my PC in the last few weeks. 

[PremierBromanov]

3 minutes ago, Caroline said:

Alright put on the safety glasses people

 

 

Just........... WHY?!! The PSU literally comes with the proper connectors, why would you even do something like that?

clearly i didnt have them when I set it up 7 years ago

[Spotty]

50 minutes ago, Caroline said:

Just........... WHY?!! The PSU literally comes with the proper connectors, why would you even do something like that?

The HX750 80+ Silver PSU was unlikely being sold new 5-7 years ago when OP bought it, it would have been replaced by Corsair a few years earlier by the newer HX 80+ Gold models. My guess would be it was purchased used and didn't include all of the cables when they bought it or they've actually had it longer than they realise and somewhere over the last decade the cables have been misplaced/thrown away. I'm not surprised it doesn't have the complete set of original cables.

[Darkwing Drex]

Yeah, bro. Just get a new PSU. If your gpu has 2 x 8-pin power connectors, use the ones that come in youre psu box. If it requires an 8x12-pin adapter, just order one. Don't pull a fly move and try to rig up some power cables.

[Guest]

On 6/14/2021 at 6:53 PM, PremierBromanov said:

my 2x Molex to 8 pin adapters will suffice.

No.  Absolutely not.

 

What happened to the PCIe cables that came with the PSU?

 

If you don't have them any more, you can literally buy them almost anywhere.  They're the standard Type3/Type 4 cables they still use today.