Select any two GPUs for comparison
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Gaming Performance Comparison

Recommended System Requirements
Game Radeon HD 6990 Crossfire GeForce GTX 660 Ti 3-way SLI
Hitman 3 73% 20%
Cyberpunk 2077 33% 7%
Assassins Creed: Valhalla 22% 15%
FIFA 21 33% 53%
Grand Theft Auto VI 87% 30%
Call of Duty: Black Ops Cold War 18% 18%
Resident Evil 8 33% 7%
Genshin Impact 33% 7%
Far Cry 6 92% 34%
The Medium 66% 16%

In terms of overall gaming performance, the graphical capabilities of the Nvidia GeForce GTX 660 Ti 3-way SLI are significantly better than the AMD Radeon HD 6990 Crossfire.

The GTX 660 Ti has a 85 MHz higher core clock speed than the HD 6990, but the HD 6990 has 48 more Texture Mapping Units than the GTX 660 Ti. As a result, the HD 6990 exhibits a 11.3 GTexel/s better Texture Fill Rate than the GTX 660 Ti. This still holds weight but shader performance is generally more relevant, particularly since both of these GPUs support at least DirectX 10.

The GTX 660 Ti has a 85 MHz higher core clock speed than the HD 6990, but the HD 6990 has 56 more Render Output Units than the GTX 660 Ti. As a result, the HD 6990 exhibits a 40.3 GPixel/s better Pixel Fill Rate than the GTX 660 Ti. However, both GPUs support DirectX 9 or above, and pixeling performance is only really relevant when comparing older cards.

The GTX 660 Ti was released over a year more recently than the HD 6990, and so the GTX 660 Ti is likely to have better driver support, meaning it will be more optimized for running the latest games when compared to the HD 6990.

Both GPUs exhibit very powerful performance, so it probably isn't worth upgrading from one to the other, as both are capable of running even the most demanding games at the highest settings.

The HD 6990 has 2048 MB more video memory than the GTX 660 Ti, so is likely to be much better at displaying game textures at higher resolutions. This is supported by the fact that the HD 6990 also has superior memory performance overall.

The HD 6990 has 207.4 GB/sec greater memory bandwidth than the GTX 660 Ti, which means that the memory performance of the HD 6990 is massively better than the GTX 660 Ti.

The Radeon HD 6990 Crossfire has 6144 Shader Processing Units and the GeForce GTX 660 Ti 3-way SLI has 4032. However, the actual shader performance of the HD 6990 is 5100 and the actual shader performance of the GTX 660 Ti is 3951. The HD 6990 having 1149 better shader performance and an altogether better performance when taking into account other relevant data means that the HD 6990 delivers a massively smoother and more efficient experience when processing graphical data than the GTX 660 Ti.

The GTX 660 Ti transistor size technology is 12 nm (nanometers) smaller than the HD 6990. This means that the GTX 660 Ti is expected to run slightly cooler and achieve higher clock frequencies than the HD 6990.

The Radeon HD 6990 Crossfire requires 750 Watts to run and the GeForce GTX 660 Ti 3-way SLI requires 450 Watts. We would recommend a PSU with at least 1000 Watts for the HD 6990. The HD 6990 requires 300 Watts more than the GTX 660 Ti to run. The difference is significant enough that the HD 6990 may have an adverse affect on your yearly electricity bills in comparison to the GTX 660 Ti.

Game FPS Benchmarks On Ultra

GPU Architecture

Core Speed830 MHzvs915 MHz
Boost Clock-vs980 MHz
ArchitectureTerascale 2 Antilles (x2)Kepler GK104-200-KD-A2 (x3)
OC Potential Poor vs Good
Driver Support - vs Good
Release Date01 Mar 2011vs01 Aug 2012
GPU LinkGD LinkGD Link
Approved
Comparison

Resolution Performance

1366x768 - green tick vs green tick -
1600x900
10
green tick vs -
1920x1080
9.2
vs green tick
10
2560x1440
6.8
green tick vs -
3840x2160 - green tick vs green tick -

GPU Memory

Memory8192 MBvs6144 MB
Memory Speed1250 MHzvs1502 MHz
Memory Bus1024 Bitvs576 Bit
Memory TypeGDDR5vsGDDR5
Memory Bandwidth640GB/secvs432.6GB/sec
L2 Cache 2048 KB green tick vs 1152 KB
Delta Color Compression no vs no
Memory Performance 0% green tick vs green tick 0%
Comparison

GPU Display

Shader Processing Units6144vs4032
Actual Shader Performance100%vs100%
Technology40nmvs28nm
Texture Mapping Units384vs336
Texture Rate318.7 GTexel/svs307.4 GTexel/s
Render Output Units128vs72
Pixel Rate106.2 GPixel/svs65.9 GPixel/s
Comparison

GPU Outputs

Max Digital Resolution (WxH)2560x1600vs4096x2160
VGA Connections0vs0
DVI Connections4vs0
HDMI Connections2vs0
DisplayPort Connections-vs-
Comparison

GPU Power Requirements

Max Power750 Wattsvs450 Watts
Recommended PSU1000 Watts-

GPU Features

DirectX11vs12.0
Shader Model5.0vs5.0
Open GL4.1vs4.5
Open CL-vs-
Notebook GPUnono
SLI/Crossfirenovsyes
Dedicatedyesvsyes
Comparison

GPU Supporting Hardware

Recommended ProcessorIntel Core i7-2600K 4-Core 3.40GHzvsIntel Core i5-3570K 3.4GHz
Recommended RAM8 GBvs8 GB
Maximum Recommended Gaming Resolution1920x1080vs1920x1080

Gaming Performance Value

Performance Value

GPU Mini Review

Mini ReviewRadeon HD 6990 Crossfire is a solution of two Radeon HD 6990 put together using AMD'S Crossfire technology.
Check the page of Radeon HD 6990 to know more about its chip.
Crossfire relies a lot on proper driver support and may suffer from micro-stuttering in lower frame rates (below 30). Benchmarks indicate the performance is overall, is only up to 10% better than a single Radeon HD 6990 performing by itself but it might be worse (depending on whether or not the 3D game supports crossfire or in the graphics driver) than a single Radeon HD 6990. Expect this combination to draw up to 750 Watt though the average power consumption should be slightly lower.
Even the most demanding games will run at the highest settings.
GeForce GTX 660 Ti 3-way SLI is a solution of three GeForce GTX 660 Ti put together using NVIDIA'S SLI technology.
Check the page of GeForce GTX 660 Ti to know more about its chip.
As usual, SLI relies a lot on proper driver support and may suffer from micro-stuttering in lower frame rates (below 30). Benchmarks indicate the performance is overall, is up to X% better than a single GeForce GTX 660 Ti performing by itself but at times (depending whether or not the 3D game supports SLI or in the graphics driver) it performed worse than a single GeForce GTX 660 Ti. Expect this combination to draw up to 450 Watt though the average power consumption should be slightly lower.
Even the most demanding games will run at the highest settings.
Recommended CPU
Possible GPU Upgrades
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GPU Variants
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