Intel UHD Graphics G1 (Ice Lake 32 EU) vs Intel Iris Plus Graphics 655 vs Intel Iris Plus Graphics 640

The Intel UHD Graphics G1 (Ice Lake with 32 EUs) is an integrated graphics card in the Ice Lake SoCs (10th generation core 10xxG1) for laptops. It is the slowest GPU version in the Ice Lake U series and offers only 32 of the 64 EUs (Execution Units / Shader Blocks). It offers no dedicated graphics memory (no eDRAM cache like the Intel Iris Graphics 655 predecessor of the Coffee Lake SoCs). The clock rate depends on the processor model. At launch it looks like all models have a 300 MHz base clock and only differ in the boost clock (1050 - 1100 MHz). Another difference is the TDP as it can be configured from 12 - 25 Watt in the 15 Watt U-models and maybe even higher in the 25 Watt models that will come later.

The performance should above the old Intel UHD Graphics 620 (Gen. 9.5) that was e.g. found in Whiskey Lake processors (thanks to the higher core count and improved architecture). Most likely the G1 graphics wont reach the performance of the old Iris Plus 640 that offered more cores and 64 MB eDRAM. Therefore, only a few new AAA games can be played fluently with the UHD Graphics G1.

A special new feature of the Gen11 graphics card is the new Variable Rate Shading (VRS) support. With it game designers can decide where to spend shading time and e.g. shade object in the background or behind fog with less resolution (up to using only one source for a 4x4 block). With this technique early results show up to 1.3x performance in Unreal Engine POC and 1.2x speedup in Civ 6. Up to now VRS is only supported by the new Nvidia Turing architecture (GTX 1650 and up).

Another improved hardware piece is the integrated video de- and encoder that was improved significantly according to Intel. They did not specify any more details, but the previous generation was able to decode VP9 and H.265/HEVC in Main10 profile with 10 bit color depth using the dedicated hardware.

The Ice Lake SoCs and therefore the integrated GPU are manufactured in the modern 10nm process at Intel that should be comparable to the 7nm process of TSMC.

The Intel Iris Plus Graphics 655 (GT3e) is a processor graphics card announced in September 2017. As the successor to the Intel Iris Graphics 650 (Kaby Lake), the Iris Plus Graphics 655 is used for 28-Watt Coffee Lake-U models. The biggest difference is the doubled eDRAM-cache at 128 MB. There should not be any big changes compared to the Iris Graphics 650.

The so called GT3e version of the Kaby Lake GPU still has 48 Execution Units (EUs), which can reach up to 1200 MHz (previously 1100 MHz) depending on the model. Besides eDRAM cache, the Iris 655 can also access the system memory (2x 64 Bit DDR3L-2133/DDR4-2400) via processor interface.

Compared to the Iris Plus 640 from the 15-Watt models, the Iris 655 only has a slightly higher maximum clock as well as almost twice the TDP, which allows a better utilization of the Turbo Boost potential.

Performance

The exact performance of the Iris Plus Graphics 655 depends on the CPU model, because maximum clock as well as the size of the L3 cache can differ a bit. The system memory (DDR3/DDR4) will influence the performance as well.

The fastest chips are high-clocked Core i7 models like the Core i7-8559U. Depending on the game, the Iris Plus 655 will probably be on par with a dedicated GeForce 930M or GeForce 940MX and can handle smooth gameplay in modern titles in low up to medium settings.

Features

The reworked video engine now fully supports hardware decoding of H.265/HEVC videos. Contrary to Skylake, however, Kaby Lake can now also decode H.265/HEVC Main 10 with a 10-bit color depth as well as Google's VP9 codec. The video output is possible via DP 1.2/eDP 1.3 (up to 3840 x 2160 @60 Hz), whereas HDMI is also supported in the older 1.4a standard. An HDMI 2.0 output can be added via converter from DisplayPort. The GPU can drive up to three displays simultaneously.

Power Consumption

The Iris Plus Graphics 655 is used for 28-Watt processor and therefore small/medium-sized notebooks.