Calling all experts - Nvidia Surround + PCIE 3.0 + VRAM

[Funkengreuven]

This is a complex question (for me) & I need some help to figure out the pros/cons & proper upgrade path. Current specs:

Win7 Home Premium
2600K
16GB RAM
P8P67 Asus Deluxe MB
2 x 240GB SSD (OCZ & Mushkin)
2 x MSI GTX680 FROZR/OC
3 x BenQ 24" 2420TX Monitors

I got the monitors last, so they had no influence on my current config. I'm going to add 1-2 680s and upgrade Mobo, Ram, & Cpu, so I can take advantage to the monitors, but before I spend the money, I want to insure I'm not creating new bottlenecks. Right now the proposed upgrade path is: CPU - 3930K, X79 Rampage IV, and Quad channel RAM. Here's my question. I know I don't want to be PCIe 2.0/3.0 limited, but I also don't want to be VRAM limited either. My 680s are not bottlenecked now on pcie2.0, but from all I've read, 3-4 cards at this resolution (5760 x 3240) will be.

Granted, I haven't tried every map; but right now if I run BF3 in auto-ultra setting the highest I've seen the VRAM usage go to is 2013MB, but no higher.

Question:Is VRAM usage affected by bus speed (i.e 2.0 vs. 3.0?) If I upgrade to x79 PCIE 3.0 (hacked), will my VRAM usage go up due to the higher bus speed?

Also, if I add more 680s, will VRAM go up on the individual cards just because I added more cards? I know the VRAM is not cumulative, but I don't understand the relationship between the two. Is VRAM usage strictly a function of game textures (and other things too)? In other words will I constantly be hitting the VRAM limit if I upgrade with 2GB cards? What about future games with more textures?

I didn't anticipate buying the monitors before I bought 2GB 680s. If so, I would have waited on 4GB cards just to be sure. But I don't want to buy more 2GB 680s if I really need 4GB to avoid VRAM limitations. You see my dilema. Selling current 680s to buy 4GB versions will be a major pain.

Anyway, sorry for the book, but it's a loaded question with no easy way to ask it. I've researched the answer, but none that I've found addresses the complete situation and provides a definitive answer.

Thanks for any help you can give me.

 

[jpardo2]

Yeah the VRAM off one card is your total availible amount, sucks, im sure that will change in the not so far future. Did you buy the 680's online or at a retail store?
If you bought them at a retail store, and most them have a 30day grace period for returns, I'd return them for a 4GB 680 (or 670, same card imo). What happens with VRAM when you're playing a game is this, the more VRAM availble, the more the game uses, and vice versa. So if you had 2GB availble it would do what it can with 2GB, but the same card with 4 GB will do what it can with 4GB. As far as bottlenecks I don't think you'd have any at all, remember your not using 2 video cards at the same time with SLI, you're using pieces of one card and pieces of another. Even though you will get double the performance (especially at the high of a resolution), it's not like both cards will be going balls to the walls.

 

[Funkengreuven]

When I loaded MaxPayne3 last night I ran into an issue.

(Wish I could insert a picture, but if you can, i don't see how...)

Anyway, here's what I'm seeing:

The bottom of the graphics setting page has a (memory available vs. memory used) number comparison. Each time you turn on/up a setting in the graphics screen it shows a cooresponding increase in the VRAM utilization. When I lower the resolution, the VRAM utilization goes down even though the settings stay the same. If I raise the resolution to surround (5880 x 1080), I run out of VRAM when I turn up MSAA fronm 2X to 4X with everything else on Max.

If I understand correctly, the game will not realize it's maximum potential (or in this case) it will not run in 4X MSAA because of limited VRAM even thought it may have plenty of GPU power to do so. With 2XMSAA and everything else set to max, I get 100+ FPS. So; if I had more VRAM, I could run 4X MSAA and still have high FPS, but can't because I'm "VRAM" limited.

This is this the VRAM bottlencek, right?

 

[jpardo2]

I wouldn't call it a bottleneck, a bottleneck is when one piece of hardware strangles another (gpu vs cpu/cpu vs hdd etc..). What your seeing is a lack of VRAM due to the insanely high resolution of 5880x1080. If that is the resolution that you want to go with, and you have it set in your head to do so, then you obviously need more VRAM. You are running three 24' Monitors with a combined resolution of 5880x1080, which requires some serious hardware to get them going. I'm not particular of AMD or NVIDIA, they both make great video cards, but in this situation I'd recommend the Radeon HD 7970. The 7970 has a large memory bus width (384-Bit, vs nvidia's 192-Bit), which means fast memory read/write from the chip to the memory itself, resulting in faster refresh rates, and in turn giving you more FPS. This is just a personal recommendation, people all have their own opinions on things, but one fact that everyone knows is AMD is a few steps ahead of NVIDIA when it comes to the multi-monitor game. I personally tested the Gigabyte 3GB Radeon 7970 ( http://www.newegg.com/Product/Product.aspx?Item=N82E16814125413&Tpk=hd%207970 ) and it did very well for one card pushing three screens, at a lower resolution of course. Plus the 7970 natively supports much higher resolutions with just a single card than nvidia does. I am sure all of the manufacturers are about the same, the gigabyte comes with three fans mounted on it for a cool running card. I would stay away from Diamond cards, I've read more than enough bad reviews about there products/warranties/rma's (I know reviews aren't everything in this world, but enough of them should mean something). Oh, last thing, when you're running that many monitors, turn vsync on, you don't wanna over work a card that is being over worked as it is.

 

[Funkengreuven]

Thanks for the insight. I didn't think about turning vsync on as in the past it's always been a fps killer. But with 120hz monitors it's definatley an option. I get your inference to 7970s and you're right, it's a little discouraging to see how few games nvidia supports in Surround/3D. If it wasn't for the folks at https://www.widescreenfixer.org/ I couldn't play anything in surround. I've always been an nvidia fan since way back when their drivers were the determining factor. It's pretty much a non-issue now, but old habits die hard. Oh well, guess I'll have to swap for 4GB cards. Maybe save a bunch with 670s instead of 680s. Thanks for the reply...