Hi Folks,
Just picked up a second GTX 660 Ti for my computer. The cards are identical but GPU-Z and GPUGRID does not appear to be recognizing the second one. Is there some sort of app_info or config file I can add to utilize both? Also, I'm assuming I do not want to put them in SLI for optimum crunching output?

Thanks

Open note pad and paste this in it

<cc_config>
<options>
<use_all_gpus>1</use_all_gpus>
</options>
</cc_config>

Save it as cc_config.xml you'll want to save it to you're BOINC folder in Application Data, not program files. I'm not sure exactly where it's at in Windows 7 but in XP it's in Documents and Settings. You'll want to shut down BOINC first and I would restart the computer after putting the file in just to make sure. As for SLI, some say it makes no difference, some say it slows down the crunching times. I wouldn't know, SLI is not supported in Windows XP for sometime now.

Doubt if it's the config file since GPU-Z isn't seeing it either, but it's a good idea to have the <use_all_gpus>1</use_all_gpus> in there anyway. Make sure the card is seated completely and both power leads are fully seated. See if Win7 sees it and it's working properly in Device Manager. If all that looks good check the BOINC event log on startup to see if BOINC is seeing the GPU. If it's still not working, try pulling the old card to see if the new one is OK. Good luck!

When you add a second GPU you still need to install the drivers for it (even if the GPU is identical). It's often the case that people leave Windows update on, and it installs some generic GPU driver or makes a mess of the installation.

On Windows, when adding an NVidia GPU it's best to first turn automatic updates off, download the latest WHQL NVidia driver. Power off the system, and at the wall/plug out. Then insert the card, boot up the system and install the drivers from the NVidia download, performing an advanced/clean install.

On Linux, if you have a repository Boinc version, after adding the GPU driver, you might need to reinstall Boinc. So best to finish work in progress. This advice might be dated, but it's certainly left a few more novice users scratching their heads in the past.

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When you add a second GPU you still need to install the drivers for it (even if the GPU is identical). It's often the case that people leave Windows update on, and it installs some generic GPU driver or makes a mess of the installation.

Interesting information. I run a number of dual AMD boxes and have never had to re-install the graphics drivers unless (like the new 7790) the old driver is lacking support for the new GPU. All my NVidia GPUs are paired with an AMD GPU so can't speak for the behavior of NV drivers though.

Thanks for the recommendations everyone. I've tried everything to no avail. I'm starting to think DOA on the second card. I tried it in another computer by itself but it will only show the MOBO introduction picture that shows up during POST and then after about 30 seconds it will go to a black screen with a flashing underscore in the top left corner. Anyone had any similar problems? Perhaps it's still something with the drivers?

As it's failed on two systems it looks like the GPU is a dud. As the second system isn't fully POSTing but starts to my guess is a leaky capacitor or bad memory. I would double check the Bios settings though. Make sure it's set to use the PCIE GPU. Again, make sure the GPU is seated correctly, and the power cable is in tight. If you didn't power the system off completely (at the wall/cable out) I suggest you reset the Bios, and then reconfigure it. Should you get nowhere RTM it.

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sure it's set to use the PCIE GPU. Again, make sure the GPU is seated correctly, and the power cable is in tight. If you didn't power the system off completely (at the wall/cable out) I suggest you reset the Bios, and then reconfigure it. Should you get nowhere RTM it.

All good ideas. You could also try swapping it into the first box, replacing the other 660 Ti that's working. If it's still no go it's a bad card.

After some more tweaking I was able to get them to work. I put one in an x16 slot and one in an x8 slot. I do however have all slots turned on (rampage iv extreme). Will all the slots being on and one card in an x8 slot create a bottle neck? Is there any way to make sure they are doing the most they possibly can? AVG GPU load on each card in 90% in GPU-Z so I think I'm probably set.

After some more tweaking I was able to get them to work. I put one in an x16 slot and one in an x8 slot.

So what was the problem and fix - Bios settings?

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After some more tweaking I was able to get them to work. I put one in an x16 slot and one in an x8 slot. I do however have all slots turned on (rampage iv extreme). Will all the slots being on and one card in an x8 slot create a bottle neck? Is there any way to make sure they are doing the most they possibly can? AVG GPU load on each card in 90% in GPU-Z so I think I'm probably set.

x8 isn't a problem, even x4 runs pretty well on this project. If they're both running at the same speed then they should get the same WU times with similar WUs.

After some more tweaking I was able to get them to work. I put one in an x16 slot and one in an x8 slot. I do however have all slots turned on (rampage iv extreme). Will all the slots being on and one card in an x8 slot create a bottle neck? Is there any way to make sure they are doing the most they possibly can? AVG GPU load on each card in 90% in GPU-Z so I think I'm probably set.

x8 isn't a problem, even x4 runs pretty well on this project. If they're both running at the same speed then they should get the same WU times with similar WUs.

DOH! Don't know what I didn't think of that :) Thanks.

Problem ended up being the socket positioning. I had them in x16 #1 & 4 on a rampage 4 extreme. That is what the manual said for SLI/CF. Perhaps since I did not have them in SLI it was upset with that?? For whatever reasoning moving the second card to slot 3 fixed everything and on boot the system recognized the card and set up drivers right away.

Up and crunching full speed ahead. Thanks everyone.