Divide By Zero - a blog by Kamran Ayub

On Friday, I spent most of the day figuring out and tuning my system to properly use SLi. I had been having below par performance and I thought that SLi probably wasn’t working.

Before I delve into the details, here’s my rig specs:

• AMD Athlon 64 X2 4200+ @ 2.4Ghz
• 2GB DDR400 RAM
• (x2) eVGA 7900GS 256MB Video Cards
• Windows XP SP3
• nVidia Drivers 175.16

I’m going to go through the different things I did to get Crysis (and my other games) properly running in SLI Mode.

The first thing I tried was updating my drivers to the latest, 175.16. In short, that didn’t seem to help. I was messing with the profile and nothing really seemed to be working, I was getting about 10-15fps. Unplayable.

Here’s what I did to make it all work:

Uninstall all previous nVidia Display Drivers from Control Panel.

Use Driver Cleaner Pro to remove the nVidia files (it’s just called “Nvidia�).

Restart the computer.

Cancel all of Windows’ driver installation boxes.

Install the nVidia drivers 175.16.

Download and install nHancer.

If you don’t already have FRAPS, download and install it to measure your FPS.

Restart the computer.

Now, here’s how to make sure SLI is actually working:

1. Open up Nvidia Control Panel
2. Make sure you have SLI Enabled
3. Click 3D Settings in the menu, click “Show SLI Visual Indicators�

Open up nHancer. It should scan your computer for installed programs. In the profiles list, scroll down to Crysis and select it.

It should look like mine above. If it doesn’t, click the profile and click the Delete (X) button above it. It should say that this is a predefined profile and you can’t delete it fully, but it will reset it to the driver’s default. That’s what you want. If the preset is still different than mine, then change the Hex Value at the bottom to my value to turn on the proper compatibility flags.

Now that we’ve enabled the SLI Load Bar visual indicator, you can start Crysis up (with FRAPS running in the background). Right away, you should see the vertical SLI bar on the right side. It’s a green bar that grows from its center, indicating whether your system is using SLI. The bigger it is, the more efficient SLI is being used. If it’s close to the center, that means that it’s mostly using a single GPU.

To test it out, load up a save game. To really test your system, you should probably keep the same settings each time you use it. My system uses these settings:

If the green bar is moving and is pretty large, SLI is working. If FRAPS shows you a decent FPS, then you know everything is as it should be.

There are a few things to know if you’re still getting crappy FPS:

• Make sure you’re using the latest Crysis Patch 1.2.
• Crysis is very GPU intensive. I get an average of 30fps using my settings and that’s good performance. It frequently is choppy, probably due to all the physics and effects, but it’s not horrible enough to make me lower the settings. Also, I don’t have an up-to-date PC by any means hardware wise.
• Don’t install a mod like the Natural Mod, it cut my FPS to about 20 normally. It’s meant for high performance PCs.
• Be sure to close all open programs and ones you don’t need from the system tray. It all uses up valuable memory Crysis needs.
• Try using the 169.44 or 169.09 drivers. They are beta drivers but they might work. I tried the 169.44 drivers and SLI first started working then. However, it was probably because I used nHancer to reset the Crysis profile to its default settings.
• Crysis is not GPU OC friendly, try disabling your overclock.

For some reason, my water is flickering and it’s annoying. It started doing that once I used SLI. It happened in the 169.44 drivers and then when I removed them and used 175.16, it still was there. It has to do with the Shader setting being set to High (or above). If it is on Medium, it doesn’t flicker.

Whatever, it works doesn’t it?

Note: In the title I said “and other games.� All of this made my other games work properly too, like Call of Duty 4, Oblivion, and Gears of War. All of which are now playable at 1680x1050 and full effects. GoW even can reach 60fps average! Oblivion is about 30-40fps average. CoD 4 can be 70fps in good areas and dip to 20s in really crazy areas.