The Intel HD Graphics (Bay Trail) is a low-end integrated Bay Trail graphics card found in certain Atom models (Z3770), nettops (J2850) and notebook SoCs (N3510). It supports DirectX 11 and is based on the Ivy Bridge GPU. Clock rates and shader cores, however, are considerably lower.
Compared to Ivy Bridge, which offers either 6 or 16 Execution Units, the HD Graphics (Bay Trail) comes with only 4 EUs. The core clock is significantly lower as well. Depending on the specific model, the maximum Turbo Boost is 896 MHz or less and the memory controller can support DDR3(L), DDR3L-RS or LPDDR3 in single- or dual-channel operation.
The fastest notebook models equipped with this GPU nearly match the performance of the HD Graphics (Sandy Bridge) and the AMD Radeon HD 6310. Therefore, older and less demanding Windows games like World of Warcraft or Half-Life 2 can be played fluently in very low settings. Performance is not sufficient for most modern titles.
Compared to competing ARM SoCs, Bay Trail outperforms the Adreno 320 (which can be found in different Qualcomm SoCs like the Snapdragon 600) and offers a performance similar to the Tegra 4 GPU. That is enough power to run even the most demanding Android games smoothly in very high resolutions as of 2013.
The integrated video decoder supports all popular codecs such as MPEG2, H.264, VC1, VP8 and MVC and is suitable for resolutions up to 4K up to 100 Mbit/s. The user can connect up to two displays via HDMI 1.4 (max. 1920 x 1080) or DisplayPort 1.2 (max. 2560 x 1600). Another new feature is the support for Wireless Display and Quick Sync, Intel's fast and power efficient H-264 hardware encoder. Some of these features are not available on all models.
Depending on the model, the power consumption of the entire SoC is somewhere between 2 and 10 W. The most efficient versions are therefore suitable for passively cooled tablets, whereas faster variants are used in larger subnotebooks with active cooling.
The Intel HD Graphics 4400 (GT2) is a processor graphics card included in some of the ULV Haswell processors of 2013. The relatively low base clock can be automatically overclocked using Turbo Boost technology. Depending on the processor model, the turbo clock rates may differ, resulting in varying graphics performance between models.
In comparison to the HD 4000, the HD 4400 graphics core has been modified extensively. The GPU now supports DirectX 11.1, OpenCL 1.2 and OpenGL 4.0. It also features an improved decoder for 4K videos and the fast Quick Sync encoder. Compared to the faster 4600, the 4400 offers the same amount of shaders, but lower clock speeds (see table of clock speeds of the different CPU models below).
The performance of the HD Graphics 4400 is somewhat below the HD 4600, since the GPU is designed for ULV models. Therefore, the clock rates are relatively low. Furthermore, the reduced TDP limits the Turbo Boost. Compared to the ULV versions of the Ivy Bridge HD 4000, the HD 4400 is about 20 - 30 percent faster. This performance boost is achieved by architectural improvements and an increased number of execution units: The GT2 version integrates 20 EUs, compared to 16 EUs for the old HD 4000. Depending on the clock rate, the HD 4400 matches the performance of a dedicated Radeon HD 7550M.
Due to the 22nm 3D Tri-Gate production process, the power consumption is relatively low. The HD Graphics 4400 can be found on ULV dual-core Haswell models with a TDP of 15 watts.
The Intel HD Graphics (Skylake) (GT1) is an integrated graphics unit, which can be found in low-end ULV (Ultra Low Voltage) processors of the Skylake generation. In most CPUs, this GPU was named Intel HD Graphics 510 or Intel HD Graphics 515 (see both pages for benchmarks and information).
This "GT1" version of the Skylake GPU offers 12 Execution Units (EUs) clocked at up to 800 MHz (depending on the CPU model). Due to its lack of dedicated graphics memory or eDRAM cache, the HD Graphics has to access the main memory (2x 64bit DDR3L-1600 / DDR4-2133).
Depending on various factors like memory configuration, the HD Graphics should perform similar to the older HD Graphics 4200 and will handle only some older and less demanding games in lowest settings.
The revised video engine now decodes H.265/HEVC completely in hardware and thereby much more efficiently than before. Displays can be connected via DP 1.2 / eDP 1.3 (max. 3840 x 2160 @ 60 Hz), whereas HDMI is limited to the older version 1.4a (max. 3840 x 2160 @ 30 Hz). However, HDMI 2.0 can be added using a DisplayPort converter. Up to three displays can be controlled simultaneously.
The HD Graphics (Skylake) can be found in mobile processors specified at 6 W TDP and is therefore suited for passively cooled 2-in-1 laptops and tablets.