Most games should run well, even on 1080p, but not at 3xIR. IR is the resolution the game is rendered at, the window or full screen resolution is what the rendered picture gets streched to. Anyways, for "higher" IR like 3xIR(which is slightly above 1080p), you do need a GPU.
So you should be able to play most games at 1xIR, but the games will be pixelated. My guess is that 2xIR is the max you can get out of your integrated GPU. You can try 2.5xIR or 3xIR, maybe it does work on some games. 2xIR means roughly 4 times the GPU power needed compared to 1xIR, 3xIR means 9 times.
So you should be able to play most games at 1xIR, but the games will be pixelated. My guess is that 2xIR is the max you can get out of your integrated GPU. You can try 2.5xIR or 3xIR, maybe it does work on some games. 2xIR means roughly 4 times the GPU power needed compared to 1xIR, 3xIR means 9 times.