Nvidia 4GB vram with 256 bit? Its cusing weird lags.

[aleksanderdev]

Hi.

First off, why dos nvidia have lower Memory Bus Width than AMD?
Nvidia has 256 while Amd got 384 bit


With my 680 4gb versions iv actually experienced wierd lagging while still having good FPS.
This happend to me while playing FarCry3 on 3 monitors (5760x1080) I first though i had low fps, but after turning settings to the lowest i had good fps but still weird lags.
Its like the GPU pushes out waves of FPS.
The only reason i can think of cusing this is that the 256 bit isn't good enough to handel 4gb Vram.
If this is true how come Nvidia produced a 4gb version with only 256 Bit,
if it cant handel more than 2 or 3gb.

Im eagerly awaiting to buy 2 of the upcomming Titans.
As its the first and only nvidia card with 6gb. (Which i need and dont tell me i dont need it.)

Titan comes with 384-bit and 6gb.
My question is than will 384 bit be good enough to handel 6gb?

 

[alvine]

dont compare memory bus as they use different architectures
what are your system specs. the cpu might be bottlenecking

 

[aleksanderdev]

Its not my cpu its at 80% load.
I have 3770k at 4,8GHz.

Now im pretty sure its the the low bus rate not being able to keep up with full loaded 4gb vram.

What els would cuse the Game to start lag, while having stable 60fps?

 

[alvine]

it can also be your ram or hard drive

 

[deathengine]

Farcry 3 is not optimized to run at 5760x1080. It will lag with any card.
Even with farcry 3 at that resolution with SLI GTX 680's it still lags and stutters at times with everything turned up. Extra memory bandwidth isn't going to help. That game is pretty hardware intensive.

 

[Fokissed]

The GTX 680 has plenty of memory bandwidth, and it can keep up with the 4GB of VRAM just fine. More memory doesn't necessarily mean more bandwidth is needed. A large amount of VRAM will reduce the thrashing to the main memory and PCIe bus, and possibly shift the bottleneck to the VRAM bus.

An easy way to test this is to enable/disable anti-aliasing (very bandwidth intensive) and see if the lag changes. If there is a significant difference, then it's likely a lack of bandwidth and you should reduce AA/AF/Mipmaping (and possibly some post-processing).

 

[aleksanderdev]

The GTX 680 has plenty of memory bandwidth, and it can keep up with the 4GB of VRAM just fine. More memory doesn't necessarily mean more bandwidth is needed. A large amount of VRAM will reduce the thrashing to the main memory and PCIe bus, and possibly shift the bottleneck to the VRAM bus.

An easy way to test this is to enable/disable anti-aliasing (very bandwidth intensive) and see if the lag changes. If there is a significant difference, then it's likely a lack of bandwidth and you should reduce AA/AF/Mipmaping (and possibly some post-processing).

Thanks a lot for your answear.
But whats weird is that while encountering this problem i was running fps log in the background with afterburner and the lowest fps i had was 35! (low settings)
Meaning its not becuse the game is poorly written performance wise/being very demanding i get this lag spikes. Its duo to something els and its not my Ram Or SSD.
As i run SSD in stripe 0 with a little over 1000 mb write read. And corsair 16gb 1866 Mhz memory.

 

[migrax]

If you want to test what you are hearing from these folks, disconnect one or two of your monitors and see if the stuttering clears up. How much vram you have on your card has no direct relationship with your card's bus width. It's apples and oranges.

A wider bus is a good thing, and having more memory is a good thing. If you take the resolution you are playing at and multiply it you get how much vram you need to display one frame. In your case you have 4gb if vram and need 6gb to buffer the resulting image. Your card is having to make 2 passes at rendering the image and then your computer is having to buffer that for your display. If you want to play at that resolution, get a single gpu with more than 6gb or get 2 cards in SLI. You are just asking too much of your hardware, plain and simple.

5670x1080 = 6220800
4gb = 4194304


migrax

 

[Fokissed]

If you want to test what you are hearing from these folks, disconnect one or two of your monitors and see if the stuttering clears up. How much vram you have on your card has no direct relationship with your card's bus width. It's apples and oranges.

A wider bus is a good thing, and having more memory is a good thing. If you take the resolution you are playing at and multiply it you get how much vram you need to display one frame. In your case you have 4gb if vram and need 6gb to buffer the resulting image. Your card is having to make 2 passes at rendering the image and then your computer is having to buffer that for your display. If you want to play at that resolution, get a single gpu with more than 6gb or get 2 cards in SLI. You are just asking too much of your hardware, plain and simple.

5670x1080 = 6220800
4gb = 4194304


migrax

A single framebuffer for 5760x1080 is 5760*1080*3 = 18,662,400 bytes. (18 MiB)
4GiB is 4*2^30 = 4,294,967,296 bytes. (4096 MiB)

As you can see, even with triple buffering the framebuffers only take 60 MiB which isn't much of the VRAM. It's other things like textures, texels, ripmaps, mipmaps, bumpmaps, lightmaps, lookup tables, etc. that use up the VRAM.

 

[TheForce]

I got the same lag on a Titan and am really surprised and looking for a fix.

I do run on PCI-E 2.0 and not 3.0, but that still should provide a sea of bandwidth to spare!

Even with GPU and video memory bandwidth usage far from their max and plenty of CPU left, as well as many gigabytes of ram free!

I suspect it is DMA related, caused by a driver or something and maybe just on PCI-E 2.0 (which is like for everyone but reviewers still).

 

[aleksanderdev]

I havent encounted any problems so far with Titan.

Tested FarCry 3, skyrim and Project Cars

Skyrim loaded 5,2GB Vram

 

[TheForce]

An update: Today i increased my PCI-E base clock from 100 to 106 Mhz in my BIOS as i expected some clock ratio to play havoc after ruling sound driver, memory and SSD caching issues, as well as almost certainly network causes. I will confirm tomorrow, but initial tests in two games seem to indicate the issue is gone now!

All i can say now is that the experience difference in games is staggering!

 

[aleksanderdev]

I got the titan now and the problems are gone.

Waiting for my second titan 😛 As 1 wasn't enough for skyrim ^^