Question I am confused about PSU connectors

[liliththroughthefire]

hey everyone! I'm new to PC building, and have a question about power supplies. Sorry in advance if this is a stupid question, but some preliminary googling didn't give me any results.
I have a MSI MAG Z790 Tomahawk, that I plan to use with a i9 13900K. For a GPU, I was eyeing a RX 7900XTX, but I noticed something about power connectors that I would like to clarify before committing.
Thing is, the motherboard has two 8-pin connectors for the CPU, and I assume you need both of those, since the i9 is really power hungry, and the 7900XTX requires three of these as well. Most "sensible" modular PSUs (<1200W) only seem to have four of these. I've done the power calculations, and I won't need much more than 750W, so buying something much bigger seems unwise. How is that power setup supposed to work then, am I missing something?
thank you.

 

[Aeacus]

Most "sensible" modular PSUs (<1200W) only seem to have four of these. I've done the power calculations, and I won't need much more than 750W, so buying something much bigger seems unwise. How is that power setup supposed to work then, am I missing something?

Don't mix up +12V EPS connectors (to power the CPU) and +12V PCI-E connectors (to power the GPU). They are different connectors and listed on different sections within PSU specs page.

For example: Seasonic PRIME TX series,
link: https://seasonic.com/prime-tx#cables

You can select from the top-right yellow box to TX-750, to see the cables it comes with.
TX-750 comes with 2 CPU (EPS) cables and 4 PCI-E (GPU) cables.

Btw, 2 PCs out of 3 i have, are also using Seasonic PRIME TX-650 PSUs. Full specs with pics in my sig.

 

[liliththroughthefire]

Don't mix up +12V EPS connectors (to power the CPU) and +12V PCI-E connectors (to power the GPU). They are different connectors and listed on different sections within PSU specs page.

For example: Seasonic PRIME TX series,
link: https://seasonic.com/prime-tx#cables

You can select from the top-right yellow box to TX-750, to see the cables it comes with.
TX-750 comes with 2 CPU (EPS) cables and 4 PCI-E (GPU) cables.

Btw, 2 PCs out of 3 i have, are also using Seasonic PRIME TX-650 PSUs. Full specs with pics in my sig.

Huh, interesting, that is good to know. So on the PSU side of things, it's the same 8-pin connection, but I gotta make sure to use the right connection cables? Anyways, that Seasonic actually looks like just what I need, I don't know how that slipped my radar. Thank you for the quick response 😀

 

[Aeacus]

So on the PSU side of things, it's the same 8-pin connection

Yes.

Here's the PSU side connectors of my PRIME TX-650, where i've also marked which cables i've plugged in:

As you can see, CPU and GPU power cables plug in to the same sockets on PSU side. But on other end of the cable, the connector is different and you can not plug e.g EPS cable to GPU or PCI-E cable to MoBo CPU power socket. Connector is keyed differently and it won't fit.

Anyways, that Seasonic actually looks like just what I need, I don't know how that slipped my radar.

Seasonic PRIME TX - flagship of Seasonic. Also, only PSU in entire world that comes with 12 years of warranty. Moreover, my TX-650 was the best 650W PSU money could buy at the time of purchase. And it still is one of the best (if not the best) PSU ever made.

My main build's PSU (Skylake build) has running solid since 2016. For missus'es PC (Haswell build), i bought TX-650 in 2020.

 

[liliththroughthefire]

Alright, that explanation makes it very clear. Thanks a lot!