So I was wondering, since this card is extremly big and looks quite heavy will I need a GPU support brace, or is the motherboard (Asus ROG Crosshair VI Hero) able to hold it?

It will be more than fine. No brace needed.

Its big but really solidly built, I wouldn't worry about that :)

EVGA_JacobF
Its big but really solidly built, I wouldn't worry about that :)

The mounting bracket is also three slots so you have 50% more than the 1080 Ti FTW3 screwed into the case.  Structurally,  its should use that extra surface area and mounting to support the rest of the card.

I do think the 3 slot design is a misstep by EVGA. A growing trend is to vertically mount GPUs in cases, of which many cases offer only 2 slot vertical mounting capabilities. I appreciate EVGA has a couple of reference based air cooled products for 2 slot , but the bulk of their differentiated air cooled product stack is looking like 3 slot solutions. Competitors are offering 2.75+ slot designs on 2 slot bracket fittings. This makes the cards viable for all permutations of fitment in most cases. Also if you put something like the FTW3 under water you will have the footprint of a single slot card requiring 3 slots to fit. I think it would be a good idea for EVGA to offer card bracket retrofit options to open up different installation requirements.

People need to learn to update their expectations. The case may provide two slots initially, but should able to be modified to fit a third slot. With cards drawing significantly more power over the last gen cards, the cooling has to expand to match.

If folks don’t want a 3 slot card, they should consider the FTW3 hybrid.

Even AI can't figure this out.
 
If you really think you may need a Brace the Current ones on the market will work fine.

 


 
They even have some for the RGB Fans
 

 

Many more Here Link