Newbie question about GPU memory

[davidst99]

Hi,

I been reading the reviews about the new Geforce 980 TI have 6GB of memory instead of 4GB on the GTX980. How big of a difference in FPS in games in 4k will the extra memory give you or is the extra memory more for software applications like CAD? Thanks.

David

 

[dave1029]

The best way to explain it is like... ok, you know grass pop-in on games? Well that grass isn't just pulled off the HDD/SSD... you have your surrounding area that is rendered, and then an increased area beyond that of data stored in VRAM waiting to be rendered. It's far faster than if the game just pulled it off the hard drive... Now when you run out of VRAM, you get horrible stutter, because the game is forced to pull new assets from the drive.

For now, 5 GB is the most you'd need. I saw a 4.5 GB draw for me on Watch Dogs, but that is the most I've ever seen. But like we saw with the 290x, a lot of people purchased that card to future proof themselves because... "when would we ever need 4GB of VRAM." We will only see more and more VRAM needed as games get more detailed and DX 12 comes out. I would say the Ti will not run into any problems in the near future at resolutions of less than 4K. At 4K, it could have a few problems on *some* games by the end of next year.

I would like to point out that VRAM will not give you more fps... It will only give you a smoother game play experience on games that would otherwise exhaust the VRAM on the other card. With that being said, the 980 Ti is far faster than the 980 regardless, and is a great buy.

 

[Udgnim]

if a game actually needs >4GB VRAM to render a scene, then the 4GB VRAM video card will have lower minimums and frame rate tanking

the >4GB VRAM video card won't

however, the >4GB VRAM rendering scene might require so much GPU that single GPU rendering doesn't produce playable framerates no matter the amount of VRAM available unless 2+ GPUs are being used

keep in mind that a game might buffer >4GB VRAM but it might never actually need more than >4GB VRAM to render a scene

 

[gamervivek]

Tiled resources will help with the reducing the memory footprint, of course textures would increase to fill that gap.

 

[TemjinGold]

Haha let's try plain English.

OP - More than 4gbs helps when your program uses more than 4gbs. For things that do not, you will see zero difference. With stuff out right now, you will not see a difference outside of a few weird corner cases. But with stuff in the next 1-2 years, no one can say for sure.

One more thing: In games in 4k right now, the GPU horsepower will peter out long before the extra VRAM comes into play (unless you are running multiple cards and multiple monitors).

 

[LTC8K6]

By the time you actually need 6gb of vram, there will be a whole host of other cards for you to choose from.

I would not buy a 6gb card now, expecting it to still do the job in two year's time.

I would buy a 4gb card now, and the future will bring what it brings. I'll upgrade then.

 

[PrincessFrosty]

The best way to explain it is like... ok, you know grass pop-in on games? Well that grass isn't just pulled off the HDD/SSD... you have your surrounding area that is rendered, and then an increased area beyond that of data stored in VRAM waiting to be rendered. It's far faster than if the game just pulled it off the hard drive... Now when you run out of VRAM, you get horrible stutter, because the game is forced to pull new assets from the drive.

This is a good explanation, what is worth understanding is that performance doesn't linearly scale with amount of memory, it's not like if you put in 2x more memory you get 2x more FPS. Rather memory will allow you to store a larger number of higher quality assets without running into issues streaming them from disk.

Typically higher resolutions require more memory especially when you have per-pixel effects running such as Anti-aliasing which increase in demand with the total number of pixels, it could be the case that some games exceed 4Gb of useage at high (4k UHD) resolutions, or soon will do, that's something you'd need to investigate. Anecdotally my GTX980 is powering my main 2560x1600 panel at the moment which is 2x the number of pixels of 1080p but about 1/2 the pixels of 4k UHD, and games like GTAV can push the memory very close to its limit.

The trick with memory is to have enough for what you need and then you see 100% of the speed that the GPU is capable of, with too little then the bottlenecks of disk reads will tank your FPS. In short it's probably better to think of amount of memory as a way of avoiding FPS dips rather than actually boosting FPS.

That is all purely talking about memory amount, memory also comes in different speeds which can help performance if the GPU is memory bandwidth starved, but that's another discussion.

 

[DaveSimmons]

Right now most games run well at 1080p with just 2 GB of RAM at normal settings, not even 4 GB. Ultra settings might give you more feathery edges to the grass blades or something but you have to stop playing to stare at the grass to notice that.

6 GB is nice to have if you plan to mod Fallout 4 with piles of custom textures, or turn on the ultra spiffy grass blades setting, or run at resolutions above 1080p with max settings. It's nothing you "need" though.

 

[dave1029]

To give you an idea of what the newest games are using, I saw a 2.7 GB VRAM usage in TW3 @ 1080p. Moving up to 4K increased that to 3.5 GB.

Edit: But in TW2, that used only 1.3 GB @ 4K. So you can see how different it is 4 years later. It will only increase exponentially.

 

[tweakboy]

Nice OC princefrosty