This is my very first post, so please forgive and correct me if I do something incorrectly. I recently purchased the new (as of May, 2018) Dell XPS 15 2-in-1 laptop which has the new Intel Core i7 8705G that has a dedicated/integrated AMD Vega M GL GPU. It is supposed to (according to benchmarks) perform in the ballpark between the GTX 1050 TI and the RX 470. When I select this GPU in the system tab of the user preferences, under the OpenCL section, I get nearly the same results (in terms of render times) when I select GPU or CPU from the render menu in the properties menu. Is there anything I am doing wrong? Also, I understand, as I am coming from a PC with a GTX 1070 that I have to adjust accordingly the Tile size in the Performance section of the render menu. What is curious to me, is that when I have it on CPU, I have to use tile sizes around 256 to 512 in order to get the best times! Which blows my mind because usually it would be 16 to 32 on a 7700K. The GPU using the same tile sizes as the CPU.
Thank you in advance to any help that I may receive.
P.S. The file that I have been using to run my tests is the AMD benchmark blend file found at http://download.amd.com/demo/RyzenGraphic_27.blend