power draw PSU requirements to handle an RTX4070 + RTX4090?

[Lantegra]

Hello, I seek advice in regards to picking a proper PSU to power both an existing RTX4070 and a to be purchased RTX4090 inside of a single computer.
A client of mine seeks to upgrade their 4070 to a 4090 for gaming, and wishes to continue using the 4070 for streaming purposes after hearing how some people do this,
and/or purchase an Intel Arc card for that purpose. He wishes to do it with his existing 4070, which is a Gigabyte RTX 4070 WINDFORCE OC 12G to be exact.

• Since it may be relevant, here are the full specs currently
• AMD Ryzen 7 7700X
• ASUS TUF GAMING B650 PLUS WIFI
• Gigabyte RTX 4070 WINDFORCE OC 12G
• Corsair DDR5 Vengeance RGB 2x16GB 6000
• WD Black SN850x 2TB
• Corsair iCUE H150i ELITE CAPELLIX XT
• Seasonic Focus GX-850
• Corsair iCue 5000X RGB Tempered Glass Black Case -> And I plan to ensure both GPUs are properly supported to mitigate any sag.

I was initially looking at the be quiet! Straight Power 12 1500W because it has the required connectors:

• 4x 6+2 pins PCI-E power
• 2x 12VHPWR

My questions are as follows:

• Am I right to assume this power supply is 'specced' for the type of use I described?
• Are there alternative power supplies fit for the job?
• Any motherboard or BIOS-related things I should be wary of?

I'm open to hearing feedback.
Thanks in advance!

[igormp]

12 minutes ago, Lantegra said:

to continue using the 4070 for streaming purposes after hearing how some people do this,

That's pretty useless, since the streaming portion of the GPU (nvenc/nvdec) is actually a different part from the actual GPU die that processes graphics, so there wouldn't be any performance gains.

 

14 minutes ago, Lantegra said:

I was initially looking at the be quiet! Straight Power 12 1500W because it has the required connectors:

That's actually really overkill for what you want, but ought to get the job done nonetheless.

[Alex Atkin UK]

I'd agree, you could probably run three 4090 off that as they never get close to the 600W theoretical maximum, its really 350-450W.

 

I have my 7800X3D + 4090 off a UPS alongside my 55" LG OLED and gaming I don't think its ever gone over 650W in total.

 

But like you said, I think keeping the 4070 in there is just a waste of energy.  Using a different card to encode means moving the frame buffer over PCIe, it actually adding more bottleneck.

 

If you really want to reduce overhead of streaming you capture the output to a different PC and let that do the streaming.  But its generally an overkill thing to do for people doing fancy stuff in OBS, I'm not sure people even bother doing that these days.

[PDifolco]

1 hour ago, Lantegra said:

Hello, I seek advice in regards to picking a proper PSU to power both an existing RTX4070 and a to be purchased RTX4090 inside of a single computer.
A client of mine seeks to upgrade their 4070 to a 4090 for gaming, and wishes to continue using the 4070 for streaming purposes after hearing how some people do this,
and/or purchase an Intel Arc card for that purpose. He wishes to do it with his existing 4070, which is a Gigabyte RTX 4070 WINDFORCE OC 12G to be exact.

• Since it may be relevant, here are the full specs currently
• AMD Ryzen 7 7700X
• ASUS TUF GAMING B650 PLUS WIFI
• Gigabyte RTX 4070 WINDFORCE OC 12G
• Corsair DDR5 Vengeance RGB 2x16GB 6000
• WD Black SN850x 2TB
• Corsair iCUE H150i ELITE CAPELLIX XT
• Seasonic Focus GX-850
• Corsair iCue 5000X RGB Tempered Glass Black Case -> And I plan to ensure both GPUs are properly supported to mitigate any sag.

I was initially looking at the be quiet! Straight Power 12 1500W because it has the required connectors:

• 4x 6+2 pins PCI-E power
• 2x 12VHPWR

My questions are as follows:

• Am I right to assume this power supply is 'specced' for the type of use I described?
• Are there alternative power supplies fit for the job?
• Any motherboard or BIOS-related things I should be wary of?

I'm open to hearing feedback.
Thanks in advance!

The 4070 will be useless with a 4090, unless you're doing AI stuff or such

Plus your board only has a x4 slot in addition to the main GPU x16 slot, not sure a GPU will even fit or work there (usually you need a x8/x8 setup with 2 upper long slots)

Sell it, and with only the 4090 your Focus GX850 will be enough