NVIDIA GeForce 940MX vs AMD Radeon RX 580 (Laptop)

NVIDIA GeForce 940MX

The Nvidia GeForce 940MX is a mid-range laptop graphics card with DirectX 12 support (FL 11_0). It has been announced in the first quarter of 2016 and is the refresh of the GeForce 940M. Compared to the older card, the new one is based on the same chip but now supports faster GDDR5. Therefore, it is similar to the Maxwell GPU in the Microsoft Surface Book but with more memory and higher clock speeds. However, most notebook vendors will use the slower DDR3 version of the 940MX that clocks only a few percent faster than the old GeForce 940M (1122 versus 1072 MHz base clock e.g.). 

For the GDDR5 version of the 940MX there appears to be also a variant with the GM107-B chip with 512 shaders instead of the 384 but lower clock speeds. The 940MX in the Acer Aspire E5-774G e.g. featured 512 shader cores (GM107) clocked at 795 - 861 MHz. The Dell Inspiron 17 7778 version however had the GM108 chip with 384 shaders clocked at 1083 - 1189 MHz.

The performance greatly depends on the used graphics memory and chip. According to our benchmarks (see below), the DDR3 version is very similar to the old 940M (due to only minor increased clock rates). The GDDR5 version however pushes ahead 20% (even 30% if paired with a fast desktop quad-core, but we lack 940M reference scores). Therefore, demanding games from 2015 should run fluently in low to medium settings and WXGA resolution. 

The TDP of the card should be rated at about 15 to 30 Watt (depending on the version, clock speeds and memory). Therefore, the GPU is best suited for laptops from 13-inch and up.

AMD Radeon RX 580 (Laptop)

The AMD Radeon RX 580 is a high-end graphics card for laptops. It is based on the Polaris 20 chip. Compared to the Polaris 10 in the similar RX 480, the Polaris 20 is manufacted in an improved 14nm process (LPP+) for higher clock speeds and some power efficiency improvements in idle. The performance in laptops depends on the used clock speeds and should be similar to the desktop RX 470 (see for gaming benchmarks) or even RX 480.

More information on the Polaris architecture and its features can be found here.