Solved

Cannot Enable SLI in Windows for Pair of GeForce GTX 660s

Posted on 2014-11-08
5
311 Views
Last Modified: 2015-01-05
Hey Guys -

I've got a home system with the following specs:
- Intel i7-3770k CPU
- 16gb of RAM
- Gigabyte GA-Z77X-UD5H Motherboard
- Dual Nvidia GeForce GTX 660 (Latest Drivers are installed)
  Note:  One has 2gb RAM and the other 3gb
- Hardware SLI Bridge connected to both video cards
- Windows 8.1 Update 1 x64

I bought the 2GB about 6 months ago when I got my Shield and the 2nd one which is 3gb about a week ago.  When playing around with benchmarks, I downloaded and opened GPU-Z to see that SLI wasn't Enabled.  I opened Nvidia Control Panel, but the option to enabled SLI wasn't even there.  Both cards do appear individually in the Nvidia Control Panel and Device Manager.

After a bit of research, I ensured everything was up to date and reseated the cards.  I even found and tried a post where I had to add 4 DWORD registry entires.  The option still doesn't appear.

I dug through the BIOS and the only video setting I saw was for if the internal one was enabled/disabled.  I tried both settings.  I also found a post that said during POST hit Ctrl-F1 which would show "hidden" options which I usually wouldn't see since I don't currently use UEFI, but that didn't do anything.  I went to Gigabytes site and downloaded the GA-Z77X-UD5H manual.  It has a page about SLI but in the Nvidia Control Panel settings, it says just to make sure "Maximize 3D Performance" was enabled.

For a minute, I thought that perhaps in newer driver versions and/or in Windows 8.1, there was no option and SLI would automatically be enabled.  However, if so I don't think that GPU-Z would have shown SLI as "Disabled."

Any ideas or suggestions?  Thanks!
0
Comment
Question by:BzowK
  • 3
  • 2
5 Comments
 
LVL 62

Expert Comment

by:☠ MASQ ☠
Comment Utility
What are the exact make/models of the two GTX660s?
0
 

Author Comment

by:BzowK
Comment Utility
Sorry for the late reply, but Thank you for yours.  Here are all the specs of each card....

GPU #1 - EVGA e-GeForce GTX 660 2GB (PCI Express 3.0 x16)
Graphics Processor Properties      
Video Adapter      EVGA e-GeForce GTX 660
BIOS Version      80.06.58.00.60
BIOS Date      4/29/2013
GPU Code Name      GK106
PCI Device      10DE-11C0 / 3842-2662  (Rev A1)
Transistors      2540 million
Process Technology      28 nm
Die Size      221 mm2
Bus Type      PCI Express 3.0 x16 @ 1.1 x8
Memory Size      2 GB
GPU Clock      324 MHz
RAMDAC Clock      400 MHz
Pixel Pipelines      24
Texture Mapping Units      80
Unified Shaders      960  (v5.0)
DirectX Hardware Support      DirectX v11
WDDM Version      WDDM 1.3
Memory Bus Properties      
Bus Type      GDDR5
Bus Width      192-bit
Real Clock      162 MHz (QDR)
Effective Clock      648 MHz
Bandwidth      15.2 GB/s
Architecture      
Architecture      nVIDIA Kepler
Streaming Multiprocessors (SMX)      5
L1 Cache / Local Data Share      64 KB per multiprocessor
L1 Texture Cache      48 KB per multiprocessor
L2 Cache      384 KB
Theoretical Peak Performance      
Pixel Fillrate      7776 MPixel/s @ 324 MHz
Texel Fillrate      25920 MTexel/s @ 324 MHz
Single-Precision FLOPS      622.1 GFLOPS @ 324 MHz
Double-Precision FLOPS      25.9 GFLOPS @ 324 MHz
24-bit Integer IOPS      103.7 GIOPS @ 324 MHz
32-bit Integer IOPS      103.7 GIOPS @ 324 MHz
Utilization      
GPU      0%
Memory Controller      7%
Video Engine      0%
Dedicated Memory      0 MB
Dynamic Memory      222 MB
nVIDIA ForceWare Clocks      
Level #1      GPU: 1045 MHz, Boost: 1110 MHz, Memory: 3004 MHz

GPU #2 - EVGA e-GeForce GTX 660 3GB (PCI Express 3.0 x16)
Graphics Processor Properties      
Video Adapter      EVGA e-GeForce GTX 660
BIOS Version      80.06.58.00.60
BIOS Date      5/7/2013
GPU Code Name      GK106
PCI Device      10DE-11C0 / 3842-2666  (Rev A1)
Transistors      2540 million
Process Technology      28 nm
Die Size      221 mm2
Bus Type      PCI Express 3.0 x16 @ 1.1 x8
Memory Size      3 GB
GPU Clock      324 MHz
RAMDAC Clock      400 MHz
Pixel Pipelines      24
Texture Mapping Units      80
Unified Shaders      960  (v5.0)
DirectX Hardware Support      DirectX v11
WDDM Version      WDDM 1.3
Memory Bus Properties      
Bus Type      GDDR5
Bus Width      192-bit
Real Clock      162 MHz (QDR)
Effective Clock      648 MHz
Bandwidth      15.2 GB/s
Architecture      
Architecture      nVIDIA Kepler
Streaming Multiprocessors (SMX)      5
L1 Cache / Local Data Share      64 KB per multiprocessor
L1 Texture Cache      48 KB per multiprocessor
L2 Cache      384 KB
Theoretical Peak Performance      
Pixel Fillrate      7776 MPixel/s @ 324 MHz
Texel Fillrate      25920 MTexel/s @ 324 MHz
Single-Precision FLOPS      622.1 GFLOPS @ 324 MHz
Double-Precision FLOPS      25.9 GFLOPS @ 324 MHz
24-bit Integer IOPS      103.7 GIOPS @ 324 MHz
32-bit Integer IOPS      103.7 GIOPS @ 324 MHz
Utilization      
GPU      0%
Memory Controller      0%
Video Engine      0%
Dedicated Memory      0 MB
Dynamic Memory      0 MB
nVIDIA ForceWare Clocks      
Level #1      GPU: 1045 MHz, Boost: 1110 MHz, Memory: 3004 MHz
0
 
LVL 62

Expert Comment

by:☠ MASQ ☠
Comment Utility
OK you won't get this to work, you'll need matching memory sizes. It was possible with some older 600 cards but not yours :(
0
 

Author Comment

by:BzowK
Comment Utility
Crap - So now I am considering replacing the 3gb with a matching 2gb so I can enable SLI.  My question is, would swapping the 3gb out for a 2gb (so it would match,) would it be worth it.

Even though I'd loose 1gb of RAM if I made them match, would enabling SLI more than make up for it performance-wise?  If so, by about how much?

Thanks
0
 
LVL 62

Accepted Solution

by:
☠ MASQ ☠ earned 500 total points
Comment Utility
You could easily lose the 1GB for the gain in performance of getting SLI enabled.

Two GTX 660's with SLI on that motherboard should see nearly double the performance of a single 2GB card.

You'll only get near the performance of the two cards with a single if you traded up to something like a GTX 590


See:
http://www.behardware.com/articles/876-10/review-nvidia-geforce-gtx-660-asus-directcu-ii-top-and-sli.html

http://www.guru3d.com/articles_pages/msi_geforce_gtx_660_twinfrozr_iii_review,25.html
0

Featured Post

Better Security Awareness With Threat Intelligence

See how one of the leading financial services organizations uses Recorded Future as part of a holistic threat intelligence program to promote security awareness and proactively and efficiently identify threats.

Join & Write a Comment

Sometimes a user will call me frantically, explaining that something has gone wrong and they have tried everything (read - they have messed it up more and now need someone to clean up) and it still does no good, can I help them?!  Usually the standa…
Great sound, comfort and fit, excellent build quality, versatility, compatibility. These are just some of the many reasons for choosing a headset from Sennheiser.
Get a first impression of how PRTG looks and learn how it works.   This video is a short introduction to PRTG, as an initial overview or as a quick start for new PRTG users.
This tutorial demonstrates a quick way of adding group price to multiple Magento products.

771 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

10 Experts available now in Live!

Get 1:1 Help Now