Cannot Enable SLI for Pair of GTX 660s

[bzowk]

Hey Guys -

A couple of weeks ago, I added a 2nd GTX 660 card to my system. The only difference was that it had 3gb as opposed to my first one which had 2gb of RAM. I also attached a hardware SLI bridge between the two. When opening GPU-Z, I found out that SLI was not enabled. Unfortunately, not only cannot get SLI enabled, but the option to do so doesn't even appear in Nvidia Control Panel!

I've done some research before posting and found a similar post about similar cards. The reason I'm posting is because I want to ask a couple of questions about the situation before deciding the next step to take...

Below the questions are the specs for both cards in detail and an overview of my system.

Questions
1. Does the post I found apply to my cards and there's no way to enable SLI or are there other software options?

2. What would have better performance - my current setup of x1 2gb 660 & x1 3gb 660 with SLI disabled - OR - a pair of 2gb 660s with SLI enabled? I'd be losing 1gb of RAM overall, but at least they'd be bridged...

3. Pertaining to the last question, what would the difference be in the scenario that's better? Huge difference, small difference, or not worth the trouble of swapping out card and I probably wouldn't notice a difference?

4. Do you have any more suggestions?

System Specs
- CPU: Intel i7-3770k
- RAM: 16gb (4 x 4gb)
- Motherboard: Gigabyte GA-Z77X-UD5H
- Graphics Cards: (x2) Nvidia GeForce GTX 660 (Latest Drivers are installed) Detailed specs below
- Hardware SLI Bridge connected to both video cards
- Windows 8.1 Update 1 x64 (Fully Patched)

Detailed Video Card Specs
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

Thanks Guys!!!

 

[WildCard999]

SLI has to have the same card and VRAM and even if you somehow manage to sli them (unofficial drivers) you will only utilize the VRAM from the lower card (2gb in your case). I would just use the 3 gb 660 and sell the other one and maybe get another 660 3gb or save up and just get a better card.

 

[bzowk]

Thanks for your reply...

I know they aren't top of the line by far, but I've already invested a lot into these cards already. Out of curiosity, if you had to assign a number between 1 & 10 (with 10 being the best performance) what would you give each of the following assuming my current setup is a "5"?

- (x1) 2gb 660 & (x1) 3gb 660 (SLI Disabled): 5 (Current Setup)
- (x1) 3gb 660
- (x1) 2gb 660
- (x2) 2gb 660s (SLI Enabled)
- (x2) 3gb 660s (SLI Enabled)

I have time to return the 3gb 660 to NewEgg, but not the 2gb one. I can use that credit to get a 2gb replacement. However, if I were to just start all over and get a new graphics card, what would you suggest as the best for the money? I have dual monitors, but only use one for gaming (1 monitor's old and lower res), do a bit of gaming, and they must be Nvidia as I use GameStream for my Shield Tablet and Shield Portable.

Thanks!

 

[WildCard999]

Thanks for your reply...

I know they aren't top of the line by far, but I've already invested a lot into these cards already. Out of curiosity, if you had to assign a number between 1 & 10 (with 10 being the best performance) what would you give each of the following assuming my current setup is a "5"?

- (x1) 2gb 660 & (x1) 3gb 660 (SLI Disabled): 5 (Current Setup)
- (x1) 3gb 660
- (x1) 2gb 660
- (x2) 2gb 660s (SLI Enabled)
- (x2) 3gb 660s (SLI Enabled)

I have time to return the 3gb 660 to NewEgg, but not the 2gb one. I can use that credit to get a 2gb replacement. However, if I were to just start all over and get a new graphics card, what would you suggest as the best for the money? I have dual monitors, but only use one for gaming (1 monitor's old and lower res), do a bit of gaming, and they must be Nvidia as I use GameStream for my Shield Tablet and Shield Portable.

Thanks!

Since you can return the 660 3gb I would get rid of that and just get another 660 2gb unless you can afford a 900 series card. Although your always better off going with 1 strong card over 2 weaker cards since sli-profiles usually aren't out by the time games are released and how much you gain depends on the games (I usually get 30-70% performance increase going from single to sli).Personally I'd go with EVGA 970 FTW 4gb video card since it seems to be the best performance for the $$$ plus it has enough vram to support games like Watchdogs/AC:Unity.