Rudso

Im planing on getting a motherboard that has Sli.... so if to say i get two 6800GT 256 video cards working together.... how much power would that be concidered? Like one 512MB video card? And how dose Sli work cuz when i connect the cord from my monitor to the graphic card their is only ONE cord. How would i connect it to two graphic cards

elf

Well one 6800gt is better than any 512mb card on the market (power is not based of amount of ram)...From what I understand, SLI uses each card to render every other line on the screen. So each card only has to process half as much as usual. You would connect the monitor to one card, and there will be a "bridge" between the two. Its a relatively new technology and I haven't gotten to play with it yet so I don't know too much about it.

There is a review and benchmarks available at Tom's Hardware

Rudso

so if each hard dose say half the work... dose that make the graphics better or the games faster... wat are the advantages of having 2 6800GT's working same time

Sarkast

It doesnt change the speed of the game - but gives you the option to improve graphic detail and appearance. Of course 2 6800s are more powerful than one - so you can turn up detail to a very high level, run the game at a very high resolution and with all the options like AA and AF on high too and still enjoy a high framerate.

You dont double the performance though - and the game you are playing has to support SLI - right now not too many do. I read a lot about people having all kinds of problems with SLI - i dont know if its really worth it (my opinion of course). But if you have uncounted cash - why not.

Rudso

But it would be a good idea to get a Sli motherboard say for the future... cuz if i get one 6800GT and say in 1 year more powerful games come out and insted of getting a totally different video card i get another 6800GT and by then a year from now most of the high end games should support Sli right? wat you think? plus i seen alot of people say this in their threads ..... AA and AF.... wat are they?

mgoldb2

Are you sure about this because to my knowledge it does not matter what game it is. Games dont use there own drivers so I would not think it dependent on the game. The video card drivers control all output so as long as the video card drivers support it it should work on any game.

I known people to use SLI on a number of games even ones out before SLI existed and it works fine.

There was problems early on but nvidia has fixed most those problems in updates to there video drivers.

Rudso

"Even Half-Life2 only gets limited benefit from SLI. At present a number of games will not run at all with SLI."

I got this from reading the link that Elf poster a couple of posts above... so wat dose AA and AF mean

Sarkast

Out of an article on www.tomshardware.com about SLI:

"Another problem with SLI is that it doesn't work with every game. In the worst case scenario, this can result in an SLI setup offering lower frame rates than a single-card system"

This isnt the only article stating this i've read lately. Somewhere there was even a list of games which worked with it (or maybe i should say the nvidia SLI drivers supported SLI for those games). I agree - it was also said that future drivers will improve this but right now SLI can still be a problem.

Sarkast

AA:

Antialiasing is the smoothing of the image or sound roughness caused by aliasing. With images, approaches include adjusting pixel positions or setting pixel intensities so that there is a more gradual transition between the color of a line and the background color.

AF:

Anisotropic filtering (AF) is a feature of some video cards that sharpens the details of the fading-away part of a 3D object that recedes into the distance. Think of the text in the titles at the beginning of the Star Wars movies that is presented in large letters and then scrolls back into the distance. As it scrolls off, it becomes fuzzy and hard to read. In a 3D image, you may want a comparable effect to retain the sharpness of an object as it recedes; anisotropic filtering does this. (Isotropic describes objects or image elements with vectors of equal value along different axes, such as squares and cubes. Anisotropic describes objects whose vectors are unequal, such as trapezoids and parallelograms.)
Since anisotropic filtering requires intense processing as image frames are presented to the display, it may affect performance. A user may want to weigh the perceived improvement in visual quality against the effect on performance.

I copied that off the web. Too lazy to type it up myself - sorry.

mgoldb2

try to use more up to date articles on SLI.

I remember that article and I also remember when that article was made. At the time only alienware was offering a working SLI and there was no onmarket SLI motherbaord(or very few). Like I said a lot has changed since that was written. for one nvidia has improved the drivers for SLI considerablly.



Those was driver issues not game issues that was causing games not to work. A game do not need to be made special to use SLI.

The lower framewrite only happens on lower resouloution. Just like when 2 cpu are used there is overhead by communcation between them. In lower resoultion this overhead cause lower fps. In high resoultion the overhead is less then the benfits. The point is it would be stupid to pay for two graphics cards to play on 800X600. I assuming if he need 2 graphics cards he plan to play on 1600X1200 where there will be benfits.

even that dated article did not say anything like a game needed to be made special to use SLI. ALl it said is in some of there tests they had crashes ( I would like to note that there tests was done very early in the development of SLI.)

elf

I am going to have to side with mgold2 on this one. The article is sort of dated and as everyone knows the technology advances EXTREMELY fast.

If you look at the benchmarks the games all work, they just don't get better fps. HL2, doom3 all work in SLI they just doesn't get the boosted FPS, and in fact score lower than a regular 6800gt

This may be because the CPU can't keep up. It may even get lower fps because the cpu has to work harder to split up the frames between the two cards. Personally I don't think even the gaming industry is ready for SLI yet...it doesn't help FPS that much (in all applications anyway) so unless you have money laying around burning a hole in your pocket I would say wait a bit.

mgoldb2

Halflife 2 you might be right but in doom 3 you definally get a fairly big boost in fps if you play on 1600X1200 ultra mode and AAX8 AFX16. Yes I admit this is a extreme case but if you speding this kind of money those the type of settings you probery want. Ther performance jump here is from 40fps in one geforce 6800ULTRA to SLI 2 geforce 6800 ultra at 70fps. That a 30fps secound boost pretty damm big.

this is slightly lower setting and look at the boost

Sarkast

OK that article excerpt was a little old. I also agree that i should've rephrased "and the game you are playing has to support SLI - right now not too many do" to "not all games are supported by the technology or drivers".

Anyways - here is an interesting article just one month old:

http://www.xbitlabs.com/articles/vid...0u-sli_14.html

Its obvious that SLI still has plenty issues to be taken care of and because SLI improves framerates in so very few games and causes so many instabilities and even lower framerates in others i'd still advise people against it - unless as mentioned before they have too much cash laying around. Then just get 2 cards and switch off SLI in the games that have trouble with it.

Fr4665

As to getting back on the topic what he asked if he should get the motherboard and one 6800 so he can upgrade later. I would totaly be for that as the 6800's will drop in price over the months and alot. SLI definatly still has some bugs and it doesnt render line after line but one card takes the upper half of the screen to render the other the lower. It works quite well as you can see in doom3 and i have seen it live and its very impressive. I personaly dont have that kind of money and im saving up for the nextgencards when ever they come out. But yeah get the motherboard and 6800gt for sli setup and wait till the price drops

ttyl

Rudso

Ok but if a say get 2 6800GT's eventualy and say i want to just play with one graphic card.... can i do that or is it always going to be played with both of the cards? and when you say next generation graphic card's... wat do you mean by next generation?

Sarkast

Yes you can switch off SLI and use just one of the 2 cards (if you have 2). I am sure with next generation he means the next set of cards thats gonna be brought on the market based on a new graphics chip. No clue what its gonna be called... Geforce 7800GT ? Radeon 1000XT ? Who knows....

Fr4665

yep, thats what i meant lol. I wonder well see for the geforces itll be the geforce fx7xxx for ATI well see lol