GPU PC Upgrade help needed

[Ahmedaborady]

I'm trying to upgrade my build to add one mote 3090 in my system

My specs
Threadripper 3975wx
Asus pro WS WRX80E-SAGE SE WIFI
ASUS ROG STRIX RTX 3090 OC EDITION
Psu: EVGA SuperNOVA 1300GP 80+ gold 1300W fully modular

Noctua NH-U14S DUAL FANS

Im no expert by any mean my question
I heard for octane and redshift and other GPU renderes i have to have 2 identical cards from same brand same edition and everything is that true?

Is my PSU 1300 will be able to handle two 3090 or i need to go to 1600w whats the recommendation?

Lastly if u can advice about SLI i know very little about that, is that something that is recommended for rendering? (Redshift, octane, unreal engine)?

 

[Jerry James]

I heard for octane and redshift and other GPU renderes i have to have 2 identical cards from same brand same edition and everything is that true?

Not really. You can add any card you like. The only issue is that the VRAM being used will be limited by the lowest available capacity unless your scene is doing calculations that can leverage out-of-core instructions. More info here - About VRAM, About out-of-core rendering.

Is my PSU 1300 will be able to handle two 3090 or i need to go to 1600w whats the recommendation?

Definitely wouldn't recommend running 2x RTX 3090 along with Threadripper on 1300W, tbh. At least 1500W would be ideal.

Lastly if u can advice about SLI i know very little about that, is that something that is recommended for rendering? (Redshift, octane, unreal engine)?

Nope, you don't need SLI for rendering. However, NVLink can come in handy if you want to combine VRAM capacities of the cards you're using.
Here's more info about NVLink. Also, if you're going with NVLink, make sure you check what Nvidia cards support it. Not all of them do.