Overview
Radeon R9 M390X 4GB is a High-End Mobile Graphics Card based on the Second Generation of the Graphics Core Next Architecture (GCN).

Architecture
Radeon R9 M390X 4GB Features a GPU Codenamed Neptune XT which is a Second Gen GCN GPU and is identical to the Curacao XT GPU used on the Desktop Radeon R9 270X.
Neptune XT has 20 Compute Units Unlocked and thus offers 1280 Shader Processing Units, 80 TMUs and 32 ROPs.

GPU
The Central Unit is Clocked at 900MHz and goes up to 950MHz, in Turbo Mode.

Memory: Speed
The GPU is equipped with fast GDDR5 and Accesses the Frame Buffer through a 256-bit Memory Interface. The Memory Clock Operates at 1250MHz.

Memory: Frame Buffer
The GPU can fill up a Memory Pool of up to 4GB. Under most circumstances, this only proves useful in certain 3D Games whose Settings Require Large Amounts of Memory.
However, because the GPU itself is too weak to work under other circumstances in which 4GB of Memory are needed - such as 4K Gaming, a Large Frame Buffer is mostly a Gimmick.

Power Consumption
With a rated board TDP of 100W, it is suited for very large laptops.

Performance
Radeon R9 M390X 4GB is essentially a fast Radeon R9 M290X 4GB.
Performance is Comparable to the desktop Radeon HD 7870.

System Suggestions
Radeon R9 M390X 4GB is best suited for resolutions up to and including 1920x1080. We recommend a Strong Processor and 8GB of RAM for Optimal Performance.