Question Educate me about video card heat and ventilation

[Sonikku]

I built a system recently with an ATX sized board and case to give my GPU the most breathing room possible as noise is an issue for me. And sure enough, my ftw 3 with its three fans and about four inches of space between it and the psu shroud has resulted in near silent operation even under load. But I had a few questions when making new builds in the future.

1: How many inches of breathing room do video cards need to be "ideal"? (Basically, the minimum amount of space a down firing gpu needs to avoid ramping up RPM for the same cooling)

2. I understand that hot air rises. It's why my case has exhaust fans at the top and top back to vent out hot air. Why then do Video Cards exhaust downwards?

3. Mini itx cases look pretty cool. My primary reason for not getting one is for the louder noise. But just how much louder is a gpu when run like this?

https://imgur.com/5HT6A16

Will it choke because of the small amount of space between it and the psu shroud?

 

[UsandThem]

1: How many inches of breathing room do video cards need to be "ideal"? (Basically, the minimum amount of space a down firing gpu needs to avoid ramping up RPM for the same cooling)

It will be different in every case (front fan location, style, number of fans. etc.), but if there is at least 2 inches, it should be fine.

2. I understand that hot air rises. It's why my case has exhaust fans at the top and top back to vent out hot air. Why then do Video Cards exhaust downwards?

The card is "upside down", with the fans on the bottom. The fans pull in air, and push it into the GPU heatsink, so technically they exhaust their air out of the sides of the card.

3. Mini itx cases look pretty cool. My primary reason for not getting one is for the louder noise. But just how much louder is a gpu when run like this?

Will it choke because of the small amount of space between it and the psu shroud?

Based on that example, I'd imagine the fans would have to spin up more because the front fan looks like it mostly covered by the front shroud portion, so the GPU will not receive a lot of fresh air from it. I'd imagine thermals would be much like what they are when people install the GPU in a vertical configuration in most cases, as it looks like the clearance is roughly the same.

My guess would be the fresh air would reach about half the card, but the backside of the card (where the GPU chip is at) would run a little warmer. But without this PC in front of me, it's tough to say for sure (different fans, different performance. Higher RPMs might overcome some of this, etc.).