historically cases had a bracket at the front to support full length cards. I even remember I once had a reference amd card that had an odd extension so that it would be supported by the forward full length brackets.
I have to admit I have not seen that front bracket for a long time. some server chassis have a bar across the top to support large cards. this would bet great except gfx card manufacturers like to exceed the pci spec for height. that bar had to be removed on my last two builds. now days I just put my case horizontal and pray.
I came here to mention the front support bracket. You'll find it on the larger AMD workstation cards more often than others, I first remember it on a FirePro reference card, and some searching turned up examples of it for the AMD FirePro V7900, and a few other models.
I've also had the vertical clearance issue since I try to rack mount all my gear now I've got a soundproof rack, its very annoying to need more than 4U of space just to fit a video card in a stable vertical orientation.
I have to admit I have not seen that front bracket for a long time. some server chassis have a bar across the top to support large cards. this would bet great except gfx card manufacturers like to exceed the pci spec for height. that bar had to be removed on my last two builds. now days I just put my case horizontal and pray.