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Gaming Performance Comparison

Recommended System Requirements
Game GeForce GT 645M GeForce GTX 675M SLI
Red Dead Redemption 2 664% 98%
Cyberpunk 2077 950% 172%
Dragon Ball Z Kakarot 371% 22%
Microsoft Flight Simulator 950% 172%
Call of Duty: Modern Warfare 664% 98%
Doom Eternal 557% 70%
FIFA 20 307% 6%
Grand Theft Auto VI 1068% 203%
Need For Speed Heat 664% 98%
Halo: Reach 143% 37%

In terms of overall gaming performance, the graphical capabilities of the Nvidia GeForce GTX 675M SLI are massively better than the Nvidia GeForce GT 645M.

The GeForce GT 645M has a 90 MHz higher core clock speed than the GTX 675M, but the GTX 675M has 96 more Texture Mapping Units than the GeForce GT 645M. As a result, the GTX 675M exhibits a 56.7 GTexel/s better Texture Fill Rate than the GeForce GT 645M. This still holds weight but shader performance is generally more relevant, particularly since both of these GPUs support at least DirectX 10.

The GeForce GT 645M has a 90 MHz higher core clock speed than the GTX 675M, but the GTX 675M has 48 more Render Output Units than the GeForce GT 645M. As a result, the GTX 675M exhibits a 28.3 GPixel/s better Pixel Fill Rate than the GeForce GT 645M. However, both GPUs support DirectX 9 or above, and pixeling performance is only really relevant when comparing older cards.

The GeForce GT 645M was released less than a year after the GTX 675M, and so they are likely to have similar driver support for optimizing performance when running the latest games.

The GTX 675M has 2048 MB more video memory than the GeForce GT 645M, so is likely to be much better at displaying game textures at higher resolutions. This is supported by the fact that the GTX 675M also has superior memory performance overall.

The GTX 675M has 163.2 GB/sec greater memory bandwidth than the GeForce GT 645M, which means that the memory performance of the GTX 675M is massively better than the GeForce GT 645M.

The GeForce GT 645M has 384 Shader Processing Units and the GeForce GTX 675M SLI has 768. However, the actual shader performance of the GeForce GT 645M is 273 and the actual shader performance of the GTX 675M is 952. The GTX 675M having 679 better shader performance and an altogether better performance when taking into account other relevant data means that the GTX 675M delivers a massively smoother and more efficient experience when processing graphical data than the GeForce GT 645M.

The GeForce GT 645M transistor size technology is 12 nm (nanometers) smaller than the GTX 675M. This means that the GeForce GT 645M is expected to run slightly cooler and achieve higher clock frequencies than the GTX 675M.

The GeForce GT 645M requires 32 Watts to run and the GeForce GTX 675M SLI requires 200 Watts. The GTX 675M requires 168 Watts more than the GeForce GT 645M to run. The difference is significant enough that the GTX 675M may have an adverse affect on your yearly electricity bills in comparison to the GeForce GT 645M.

Game FPS Benchmarks On Ultra

GPU Architecture

Core Speed710 MHzvs620 MHz
Boost Clock-vs-
ArchitectureKepler GK107Fermi GF114 (x2)
OC Potential Fair vs None
Driver Support Good vs -
Release Date01 Oct 2012vs22 Mar 2012
GPU LinkGD LinkGD Link
Approved
Comparison

Resolution Performance

1366x768
6.4
green tick vs -
1600x900
4.9
vs green tick
9.3
1920x1080
3.4
vs green tick
7.3
2560x1440
2.4
vs green tick
5.3
3840x2160
1.5
green tick vs -

GPU Memory

Memory2048 MBvs4096 MB
Memory Speed900 MHzvs750 MHz
Memory Bus128 Bitvs512 Bit
Memory TypeDDR3vsGDDR5
Memory Bandwidth28.8GB/secvs192GB/sec
L2 Cache 256 KB green tick vs 0 KB
Delta Color Compression no vs no
Memory Performance 0% green tick vs green tick 0%
Comparison

GPU Display

Shader Processing Units384vs768
Actual Shader Performance13%vs46%
Technology28nmvs40nm
Texture Mapping Units32vs128
Texture Rate22.7 GTexel/svs79.4 GTexel/s
Render Output Units16vs64
Pixel Rate11.4 GPixel/svs39.7 GPixel/s
Comparison

GPU Outputs

Max Digital Resolution (WxH)4096x2160vs2560x1600
VGA Connections0vs0
DVI Connections0vs0
HDMI Connections0vs0
DisplayPort Connections-vs-
Comparison

GPU Power Requirements

Max Power32 Wattsvs200 Watts
Recommended PSU--

GPU Features

DirectX12.0vs11
Shader Model5.0vs5.0
Open GL4.5vs4.1
Open CL-vs-
Notebook GPUyesyes
SLI/Crossfirenovsno
Dedicatedyesvsyes
Comparison

GPU Supporting Hardware

Recommended ProcessorIntel Core i5-3210M 2.5GHzvsIntel Core i7-3610QM 4-Core 2.3GHz
Recommended RAM4 GBvs8 GB
Maximum Recommended Gaming Resolution1366x768vs1920x1080

Gaming Performance Value

Performance Value

GPU Mini Review

Mini ReviewOverview
GeForce GT 645M is a Fast-Middle-Class Mobile Graphics Card based on the first revision of the Kepler Architecture.

Architecture
The Kepler Architecture was NVIDIA's big step to power efficiency. Each Stream Multiprocessor (SMX) now hosts 192 Shader Processing Units - against the 48 of older Fermi Architecture, and has been redesigned being now clocked at the same speed of the Central Unit. This means they are more energy efficient and will consequently lead to cooler operating temperatures. However, it also means they are weaker. It can be said that one Fermi SMX is as fast as 2 Kepler SMXs.
Additionally, and not available in all GPUs, Kepler also introduced the Boost Clock Feature. The Boost Clock is an even higher Clock Speed activated when in gaming mode and becomes the effective speed of the GPU.

GPU
It equips a GPU Codenamed GK107 which has 2 Stream Multiprocessors activated and thus offers 384 Shader Processing Units, 32 TMUs and 16 ROPs. The Central Unit is clocked at 710MHz.

Memory
The GPU accesses a 2GB frame buffer of DDR3, through a 128-bit memory interface. The size of the frame buffer is exaggerated and in no way benefits the GPU. The Memory Clock Operates at 900MHz.

Features
DirectX 11.0 Support (11.0 Hardware Default) and support for Optimus, CUDA, OpenCL, DirectCompute, 3D Vision Surround, PhysX, Realtime Raytracing and other technologies

Power Consumption
With a rated board TDP of 32W, it is suited for small laptops.

Performance
Gaming benchmarks indicate its performance stands somewhere between GeForce GT 640M & GeForce GT 650M.

System Suggestions
We recommend a decent processor (Intel Core i5 Mobile) and 4GB of RAM for a system with GeForce GT 645M.
GeForce GTX 675M SLI is a solution of two GeForce GTX 675M put together using NVIDIA'S SLI technology.
Check the page of GeForce GTX 675M 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, about 35% better than a single GeForce GTX 675M 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 675M.
Even the most demanding games will run at the highest settings.
Recommended CPU
Possible GPU Upgrades
N/A
N/A
GPU Variants
-
-

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