"Personally, I'm not a fan of going all out on VRAM size, none of our benchmarks show any noteworthy performance issues arising from 8 GB VRAM capacity. Actually, it seems likely DirectStorage, a technology that was first pioneered on the new consoles, will reduce VRAM pressure by optimizing the disk to GPU memory path."
Wizzard, you have Doom Eternal in the review. That game at 4K does show differences between 8GB cards and 10 or more gig cards. I dont know where you test, I presume it is the tiny 1st level of the game, but on my old RTX 2080 switching to the otherwise slightly weaker (at 1440p and 1080p) GTX 1080 Ti led to higher averages and Lows. I test in Blood Swamps (DLC level) or Urdak (large end-game mission).
It is still playable on 8GB with ocassional stutters (its less playable in end-game levels that are bigger and with more memories), so the game likely isnt going MUCH above 8GB, but it is definitely using more. RX 5700 XT also had the same issue. RTX 3080 10GB and RX 6900 XT 16GB dont have a problem at all.
Also... as for allocation and usage lol.
Games don't allocate memory in the sense of "give me 10GB, I'll throw my stuff in that pool". They allocate mem only for stuff that is needed, +-some granularity loss. If a game "allocates" 10G, there is indeed 10G of data in use. The catch is that not all of this data may be required to draw a given frame right now. Let's say you're in a cube where each side has a different texture, you can only see at most 5 sides at any point in time - does that mean the mem for the 6th wall is "allocated but not used"? No. If you turn around, it will need to be rendered - meaning if you didn't have the VRAM required to hold that 6th texture, you would get a lag spike when you turn around as it swaps it back into VRAM in place of the wall that just became invisible. Then if you turn around again, you will have to swap VRAM again... In big games there usually isn't a single place in an area where you can see every single asset that is in the scene - so you can in fact get away with lower VRAM than what the game calls for but you will see higher frametimes as you start moving around and start running into assets that spilled over into system RAM previously. Especiall if you actually play the game you know, move around and are in it for more time than 1-10 minutes.
That is why VRAM testing is tricky. It is not easy to do via normal short tutorial benches.
Other games that use more VRAM are Wolfenstein 2 (use actual max settings, not the preset), Cyberpunk with RT at 1440P+, supposedly the new US propaganda games (CoD) too. For Wolfenstein and CB2077 I am 100% certain though.
