My SLI really working?

Y

Yaden

Gawd
Joined
Sep 30, 2005
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529
So, today I recieved my second XFX 7800 GT, was going to wait but got spooked by rumors of Nvidia discontinuing the chipset.

First I found it odd the XFX manual says to use the lower card for the monitor, where my MSI mobo manual says top (which worked). I switched the SLI chip on the mobo, put the SLI bridge on the cards, and both are hooked up to my PSU. I go into display properties and to advanced settings, under Geforce 7800GT tab and under SLI multi-GPU I can enable SLI mode. When I first turned it on, I don't recall if it made me restart. When I turn it on/off now, my screen flashes but doesn't ask for a restart (and I didn't see any pop-up bubble saying it is on).

Before I went SLI, I ran some benchmarks with FarCry. I ran them again with SLI but got very similar results, this made me wonder if SLI is truely working. I did play FarCry on ultra-high textures and 2x AA, 8x AA, 1280x1024 and it was absolutely smooth. The benchmark results really puzzled me, am I missing something obvious?

http://bmikkelsen.home.mchsi.com/single.htm
http://bmikkelsen.home.mchsi.com/sli.htm
 
The "show load balance" line shows up in FarCry and KOTOR2, so it must be working. :eek:
 
The fastest way to make sure SLI is really on, is enable GPU load balancing (in the same menu where you enable SLI) and if you get the green lines when running 3D apps, then it's on. SLI really shines with all the eye candy on and at high resolutions... try turning the AA up to 4x and the AF up to 16x and test again... also try 1600x1200 if your monitor supports it.. I noticed FEAR and CoD2 and Quake4 really like SLI a lot... their performance increased quite a bit with SLI on for me... FarCry is likely not the best game to test SLI with... imo.. If you have any of the other three I mentioned, try them.. or grab the FEAR demo if you don't have the reg'd ver. also make sure you are running the most current patch levels on your games, as enhancements to allow some games to take full advantage of SLI were added via patches.. Anyways... sounds like to me it's working, but you need to find the right games and settings to see it shine.. it will.
 
Your image links are pointing to "c:" and are broken I think.
Click to expand...
The benchmarking tool puts the image there and it doesn't work for me either. It has nothing to do with the results so don't worry about it. :)

I don't have FEAR but maybe I will try that demo if I find some time. Next game for is Oblivion, naturally I am hoping the SLI helps there. The load balancing display is a little odd, I am reading up on that right now (but it is working, thanks).

If I simply check off "enable SLI mutli-GPU", is that allow me to benchmark single card performance without physically remove the second card?
 
Yes - but the system is still managing the other card at idle, so you're getting worse than single card performance... to really disable it, you need to change back to non-SLI mode in hardware (on the mobo) and pull the SLI bridge. But that's a bit drastic just for testing and benching.. etc.. I would only do that if there was some horrible compatibility issue going on... I have yet to run into one tho... I have been running SLI for almost a year, and not once have I had to disable it for any reason really. :) Doom3 is another game with likes SLI.. (obviously - because Quake4 uses that engine) so you can try testing with that game also. have fun!!
 
Just follow up, I have a few more questions if anyone could lend a hand...

Why are most game's "SLI rendering mode" listed as Predefined? So SLI simply works automatically?

I'm a little confused by MSAA / SSAA concept, is this something that works on top of normal AA? I can't find a good explanation of it so far. :confused:
 
alternate frame rendering means each frame is rendered by a single card. frames1,3,5,7 and so on by one card, 2,4,6,8 by the other. i think this is what is used on d3d games.
alternate frame rendering 2 is probably much like alternate frame rendering 1, but either a little newer, or just the 1 after.
split frame rendering the screen is split into top and bottom, and the cards fight over the territory. this is used in opengl games. i think if the screen is simple to render, only one card is in use, or mostly one card.
if you use the gloabal driver settings rather than the profiles, you can switch between these to some extent. otherwise it is predifined to alternate/d3d and split/ogl

sli antialisaing is like the guy above links to, i guess.

best way i found to tell if they are both working is open the nvidia display console to the temerature settings page. then play you game for a few minutes and then alt/tab out. check to see if the temps on both cards are near the same.

with newer drivers you dont have to restart when entering or exiting sli. but it be blinking a few times. only time i had to disable sli is the first time i went to mce2005 interface and it glitched out. had to disable sli until i used the xp mce drivers.
 
http://www.tweakguides.com/NVFORCE_6.html

This was pretty helpful too. From playing around, I have to go under Global Driver Settings first and change SLI rendering mode before I can enable SLI AA under games. For SLI rendering mode I can set it to "SLI multi-GPU rendering", "SLI single-GPU rendering" and "SLI antialiasing," I don't see anything about changing AR and split-frame ability. Changing options with the Global settings seems a little odd but think I am getting the hang of it.

Now to play around and see how a few games look with some of these options on.
 
Okay, let me ask a real dumb question on this with HardOCP in mind. Does "4x tr msaa" simply mean Transparency AA is set to multisampling and base AA is at 4x?
 
Yaden said:
For SLI rendering mode I can set it to "SLI multi-GPU rendering", "SLI single-GPU rendering" and "SLI antialiasing," I don't see anything about changing AR and split-frame ability.
Click to expand...

Sorry for bringing back this thread, but I still can't seem to find anything out there in regards to the rendering modes "single GPU" and "multi GPU" using forceware 84.21 (SLI zone, tweakguides, hardocp). I am using 2 x 7800GTX OC cards and even though the drivers are choosing the correct profiles for the SLI listed games regardless, I still haven't seen any info as to whether or not one should enable "single GPU rendering" or "Multi-GPU rendering" and if its just as simple as it sounds (single GPU rendering uses 1 card and multi GPU rendering uses 2 cards)?

I HAVE found much information in regards to "SLI antialiasing" rendering mode, but not the first 2 modes.

Anyone got a clue bout this??
 
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