Hi All,

Just curious as i'm thinking of buying a second 8800GTX for SLI in the next month.

What kind of performance differences are there between a mobo that runs the PCIE slots at 8x and one that runs them at 16x?

Reason i ask is because i would rather spend half the money and buy a cheaper board if there is no major difference. In New Zealand it will cost me around $200 for a good SLI 8x mobo from Asus.

A fully-fledged 16X board will cost me at least $500 however.

Can someone lend some guidance on this?

Less then 5%.

Bandwith is not really importent for graphics card.
The idea with the fast connects like AGP and PCI-E, is to be able to
have small amount of v-ram and user ordinary ram from the computer.

So bandwith is no problem as long you have enought of Vram.

Guess:
128 meg for 0.7 megapixel resolution
256 meg for 1.6 megapiexel
512 meg for 2mega
1024 meg for optimal 4 mega.

There are no games that use 1024 even at 4megapixel. 512 is ok.

Actually in DX10 games, at very high resolutions there could be up to a 20% difference with the 8800s.

Thanks for the reply Shompa.

Good to know i don't have to save up for one of these overpriced mobo's.

@Track - is there anything to substantiate this? I've been too busy to look for any DX10 benchmarks. What feature of DX10 would cause bandwidth to take on more significance?

Theres always substantial evidence to what I say, but i dont seem to remmember what review its from.

And its not a feature of DX10, its got nothing to do with Direct3D.
Its the 8800s and their incredible performance wich requires more bandwidth. Possibly having to do with the shader archtiecture.

To piggy-back on what Track is saying a little bit, I remember reading (I think in MaximumPC?) about the difference when I was trying to decide between the 650 and 680 series mobo's since one of the noticeable differences was the 2x8 or 2x16. anyway, the article talked about how right now there isn't anything that would push that hard meaning that it wouldn't even need either one to be at 8x. it did say though that dx10 future programming will push everything past that and require it due to Vista dumping so much onto the gpu as opposed to the cpu, plus the additional dx10 features and architecture.

what track is saying is also backed up i guess through nvidia's claims on the newer architecture for the g84 and g86 to be able to process hdcp, etc. with the smaller 128bits as opposed to the beefier (but older arch.) g80's.

well, this all made sense in my head, hopefully it does typed out too lol.

Well, the 8600s dont need a 16x slot because they are much less powerfull.

Also, it dosent have anything to do with Vista.

how would it not have anything to do with vista? you may be right but i don't understand how because one of the major overhauls of vista is offloading much of the power from the cpu to the gpu - and not just for aero because the requirements for the basic call for a decent gpu also. am i missing something?

and yes, the 8600's and lower are less powerful - that was part of the explanation that i figured wouldn't need to be said, BUT they are "supposed" to be able to do a lot with smaller bandwith which is where they are so far falling very short...i was very disappointed since i was waiting on those to come out and then ended up just getting the 8800gts320.

Vista does not offload anything to the GPU. The GPU has its own things to do and the CPU has its own things. Vista does take more off of the GPU when not gaming, but it does not make the GPU perform any of the tasks that the CPU is supposed to be performing.

And i really dont understand what ur saying about the 8600 GT. It has less memory bandwidth, yes. It needs less PCIe slot bandwidth, yes.

So you an afford two 8800GTXs, but you can't afford a decent motherboard with dual 16x slots? You can't find anything like this in New Zealand?
http://www.newegg.com/Product/Prod [...] 6813131153

In all likelihood, it won't make a huge difference to performance, but I figure if you're going to spend $1200 USD on videocards, you can afford the right motherboard.

@Heyyou27: LOL mate that was exactly the model i was looking at. Seems to be the best for the price.

@Track: I guess if it's going to make a bigger performance difference in the longrun, i could always upgrade later, especially since there will likely be newer and better processors out that will require an upgrade (e.g. Penryn).

For now though, i would rather save myself a few hundred seeing as i don't get the money for this kind of upgrade very often.

Yeah I see, it's not that big of a deal. What kind of monitor are you playing with anyways? I've got a single 8800GTX @ 633MHz/2050MHz and I play at 1680x1050. If you're not playing at a resolution of 1920x1200 or higher, you're likely going to waste money buying a second 8800GTX.

I'm exactly the same as you mate. 1680x1050 with a single GTX. My monitor is a 22" widescreen.

I started up Quake 4 the other day - i play at Ultra settings with 2xAA and 4xAF. I was quite disappointed that FPS could drop below 60 at those settings - my old 7950GX2 could to better .

I thought getting a second GTX could solve all my performance woes...but now i'm not so sure...the other concern i have is how well they will do in DirectX 10 as these newer games are very close at hand.

Maybe better to wait for the second generation of DirectX 10 cards that should perform a lot better. In my experience games like Crisis are made with the next generation hardware in mind so that they evolve into their prime. If history repeats itself (i'm thinking of Oblivion), the 8800s will most likely struggle quite frequently.

What are your thoughts on this?

Your 8800 GTX cant do Quake 4 @ 1680x1050 with 2xAA?

Uh.. do u have an Athlon XP? You should be getting 60+ at 1920x1200 with 4xAA.

Alas if i could get that kind of performance...what a dream. That's why i got this card in the first place lol. My specs are:

Windows XP Pro SP2
Intel Core 2 Duo E6600 @ 2.93 GHz
EVGA 8800GTX 768MB 630/2060 with Forceware 158.22
2GB DDR2 667
Creative Audigy 2 ZS
Gigabyte GA-965P-DQ6
Enermax Galaxy 1000W
Antec 900

It's quite a good system but Quake 4 seems to croak. For example, at 1680x1050 with Ultra High settings, changing the AA from 2x to 4x will yield drops to 40fps in many places.

I am really not sure what is holding this system back. I've done all basics e.g. closing all background programs, virus/spyware checking, defragging etc.

Did you enable multi-cpu in advanced settings, maybe that will help?
I just ran quake 4 on my new system and it never gets below 60 (can't disable v-sync though) on ultra at res 1680*1050

Specs are:
E6700 @ 3.333
G.skill @ 667 4-4-4-12-1T
P5N32e-sli plus
EN8800GTX (default clocks)
Creative X-Fi Fatality
Galaxy 1000
Thermaltake Shark

Like i said , absolutely no slowdowns but due to the v-sync thingie i can't see max FPS.

btw I use the same version drivers so no difference there\

Alas if i could get that kind of performance...what a dream. That's why i got this card in the first place lol. My specs are:

Windows XP Pro SP2
Intel Core 2 Duo E6600 @ 2.93 GHz
EVGA 8800GTX 768MB 630/2060 with Forceware 158.22
2GB DDR2 667
Creative Audigy 2 ZS
Gigabyte GA-965P-DQ6
Enermax Ga