660ti 2gb essentially 1.5gb?

[deannewb]

So based on my experience I've never seen my 660ti ever use more than 1.5gb of ram.
I looked into it and realized that the 192 bit bus is a mismatch with 2gb ram. it has 3 64 bit controllers for 512mb then what happens to the lat 512mb?

It got me thinking about the gtx 670 how it is has 256 bit bus scales perfect with 2gb and has more bandwidth.

Anyways I only play on 1080p and I use msaa up to 4x. So far I haven't ran into any real lag in any of my games but for some reason I feel like I'm bottlenecking my cards full potential cuz it never goes past 1.5gb.
In practice I probably won't need more than 1.5gb but the card was advertised as 2gb and I feel disappointed.

 

[COLGeek]

I think you are comparing apples and oranges here comparing the relative bandwidth (192mb vs. 256mb) and memory utilization. The bandwidth is really just the size of the data pipe between the on-board memory and the GPU.

More likely, than not, your use only hits 1.5GB of use because that is all that is needed at the resolution/settings you are using.

 

[deannewb]

One of the games I'm planning to play is skyrim with lots of mods. I looked everywhere and hardly anyone there talks about how a 660ti performs. Just 670s 680s, 580s and radeon cards.
Oh and here's a link of someone in a similiar scenario.
http://www.overclock.net/t/1307470/660ti-only-1-5gb-usable

 

[COLGeek]

Understood, it may simply be a game issue (with Skyrim). Honestly, I wouldn't sweat it.

 

[deannewb]

lol I'd rest my case if someone can prove that the 660ti can go past 1.5gb. It is rumored that if it does go past 1.5 the last 512mb will go at a slow 48gb/s?

If that is true man I feel jipped. I fully understood the bandwidth constraint as a compromise over the gtx670 but this too? ugh.

 

[Novuake]

Yeah you are mostly correct in that the GTX660ti can only effectively use 1.5GB thanks to the 192bit bus.

http://www.anandtech.com/show/6159/the-geforce-gtx-660-ti-review/2

This is THE MAIN REASON I own an HD7950 instead.

 

[COLGeek]

While the article does highlight a design limitation of the 660Ti, that limitation does not preclude using all 2GB of memory (albeit less than optimal).

 

[Novuake]

While the article does highlight a design limitation of the 660Ti, that limitation does not preclude using all 2GB of memory (albeit less than optimal).

"This invokes the worst case scenario, where only 1 64-bit memory controller is in use and thereby reducing memory bandwidth to a much more modest 48GB/sec."

Actually using the extra 512MB of RAM would actually SLOW DOWN rendering performance thanks to that nice underlined bottleneck.

But that's beside the point. Many games actually are unable to use that extra 512MB of RAM at all thanks to the complexity of the controller setup and the fact that this setup is unique to only the GTX660ti.

 

[COLGeek]

"This invokes the worst case scenario, where only 1 64-bit memory controller is in use and thereby reducing memory bandwidth to a much more modest 48GB/sec."

Actually using the extra 512MB of RAM would actually SLOW DOWN rendering performance thanks to that nice underlined bottleneck.

But that's beside the point. Many games actually are unable to use that extra 512MB of RAM at all thanks to the complexity of the controller setup and the fact that this setup is unique to only the GTX660ti.

Exactly. While inefficient (and I am sure controlled by the drivers to actually prevent it most of the time), all of the memory can still be used in a sub-optimal state.

This speaks poorly of the design.

 

[Novuake]

Exactly. While inefficient (and I am sure controlled by the drivers to actually prevent it most of the time), all of the memory can still be used in a sub-optimal state.

This speaks poorly of the design.

Glad we agree.

 

[Mt Power]

Exactly. While inefficient (and I am sure controlled by the drivers to actually prevent it most of the time), all of the memory can still be used in a sub-optimal state.

This speaks poorly of the design.

I do recall reading something about this in the driver info, from nvidia. it is a limitation!

 

[Novuake]

I do recall reading something about this in the driver info, from nvidia. it is a limitation!

He has said as much.

 

[Mt Power]

He has said as much.

...well thanks! just pointing out he may want to read through he driver info page!

 

[Novuake]

...well thanks! just pointing out he may want to read through he driver info page!

Just checking...

 

[Mt Power]

Just checking...

I never read through the driver info stuff in the past(as i suspect most dont : ) it gives more help then i realized!

 

[Novuake]

I never read through the driver info stuff in the past(as i suspect most dont : ) it gives more help then i realized!

lol I don't bother most of the time either. Usually end up just installing the latest and keeping or downgrading by trial and error.

 

[Mt Power]

Is long as you have 4GB, you are good. Any more is a total waste because games are written to be compatible with 32-bit OS, they can't possibly use more than 3.5gb of RAM. Same thing with GPUs.

if a game, like crysis for instance, has a 64bit mode it would utilize for ram, correct?

 

[Novuake]

So based on my experience I've never seen my 660ti ever use more than 1.5gb of ram.
I looked into it and realized that the 192 bit bus is a mismatch with 2gb ram. it has 3 64 bit controllers for 512mb then what happens to the lat 512mb?

It got me thinking about the gtx 670 how it is has 256 bit bus scales perfect with 2gb and has more bandwidth.

Anyways I only play on 1080p and I use msaa up to 4x. So far I haven't ran into any real lag in any of my games but for some reason I feel like I'm bottlenecking my cards full potential cuz it never goes past 1.5gb.
In practice I probably won't need more than 1.5gb but the card was advertised as 2gb and I feel disappointed.

A program like HWInfo64 will tell you exactly how much VRAM and bus width you are using.

It may be a slight mismatch to only have a 192 bit bus but my GPU has a 192 bit bus and I've never used more than 15% of it even with maxed graphics, 1080, etc. You shouldn't worry about it either.

You are also not going above 1.5g VRAM because none of your games likely use that much VRAM. To use that much VRAM you're gonna have to crank AA to like x16 or x32.

You are basically complaining that your GPU is so strong that it can handle your games on low settings with very little utilization. You gotta raise your graphics settings to really stress it, with AA as little as 4x you are not stressing your GPU at all, when it's basically made to handle extreme AAs.

Also, VRAM is totally different than GPU strength. It's just like actual RAM. Once you have enough VRAM for the program in question, having more isn't going to make things any faster. And most games really aren't going to use much more than 1GB of VRAM, especially first person shooters and only 4xAA.

There is no bottleneck going on. The term bottleneck is highly misused but I can assure you, no bottleneck exists here.

"This invokes the worst case scenario, where only 1 64-bit memory controller is in use and thereby reducing memory bandwidth to a much more modest 48GB/sec."

Actually using the extra 512MB of RAM would actually SLOW DOWN rendering performance thanks to that nice underlined bottleneck.

But that's beside the point. Many games actually are unable to use that extra 512MB of RAM at all thanks to the complexity of the controller setup and the fact that this setup is unique to only the GTX660ti.

I would hardly call anandtech authoritative, but very rarely will a game even use more than a quarter, maybe a half, of the bus width on a 660ti.

What you want in a GPU is performance. An issue like this is hardly an issue at all.

Don't forget, the lower the bus bandwidth and less VRAM your card has, the higher your card can overclock relative to higher memory and bandwidth models. I specifically chose the GTX 460 768mb GPUs back in the day, for example, because they will overclock at least 50mhz+ over a comparably binned 1GB model.

And 10mhz of extra core speed, is more important for performance than a bigger bus width or more VRAM. As long as you have enough, you are good.

It's like the issue of how much ram to get for a computer. You have no need for more than 4GB of RAM for a gaming computer, as long as you have 4GB, you are good. Any more is a total waste because games are written to be compatible with 32-bit OS, they can't possibly use more than 3.5gb of RAM. Same thing with GPUs.

Although I do agree with you that the bottleneck term is overused. In this case its as clear as day. Anandtech is not the only site to agree on this and to be honest it makes perfect bloody sense.

Actually VRAM usage is not connected that much to AA. When maxing out AA EVERY SINGLE AVAILABLE bit of memory bus width CAN be utilized.

You clearly do not play at a higher resolution.
At 1080p my HD7950 uses 2.2GB average in intense new games(BF3, FC3).

Now please tell me your sub-par GTX460 did not feel a performance hit when you tried newer and better games at higher resolutions compared to the normal GTX460?

 

[Novuake]

if a game, like crysis for instance, has a 64bit mode it would utilize for ram, correct?

Ignore that specific comment of his, it DOES NOT MAKE SENSE...

1. Last I checked 3.5GB is still larger than 1.5GB.
2. 32 and 64 bit windows memory addressing ahs nothing to do with graphics VRAM. It is managed independently by drivers. Otherwise you could only have a full total of 4GB of graphics VRAM + RAM + Cache in YOUR WHOLE DAMN system.

Seriously belial??? You CAN NOT believe that statement...

Or I will not find you credible ever again.

 

[deannewb]

Best answer selected by deannewb.

 

[Novuake]

You must be joking???

 

[jessterman21]

Just got my GTX 660 last week and I've been testing it since then. For resolutions up to 1920x1200, you're golden until you start applying 8xMSAA or texture mods.

As discussed in this thread and in last year's AnandTech review, with the 192-bit memory interface, you can only make effective use of 1.5GB of VRAM. In my experience, the card will essentially throttle once you hit about 1510MB and try not to use any more (must be some algorithm of Nvidia's), and you'll start getting lots of input lag and high frametimes, though average framerate stays nearly the same. The effective memory speed really does drop 3x lower at that point.

Crysis Warhead is a good game to test this on - Stock game with Texture Streaming off uses 1480MB at 1200p and 2xMSAA.

I agree, totally sucks that it's basically a 1.5GB card, since I bought it to better handle the texture packs I use in Crysis 1&2 and Skyrim.