It has been a few months, but I have something new regarding this issue:
I ran an OpenGL app (Qt 5.3 now, if that is relevant) on 4 different computers:
My own PC (desktop, NVIDIA GPU, the only one of the test computers with Qt installed)
Another desktop PC with an NVIDIA GPU
A desktop PC with an integrated Intel GPU
A laptop with an AMD GPU
ALL PCs are running on Windows 7.
The test consists in drawing a Rubik's Cube, with colors only and with textures.
Now for the results:
NVIDIA (both PCs):
** [url=https://dl.dropbox.com/s/udcg7jxvaxdbj8e/rubiks_pc_nvidia.png]Without textures[/url]
** [url=https://dl.dropbox.com/s/ojipiz57vu6bbuk/rubiks_pc_nvidia_t.png]With textures[/url]
AMD
** [url=https://dl.dropbox.com/s/v11hgyjas9s07i8/rubiks_pc_amd.png]Without textures[/url]
** [url=https://dl.dropbox.com/s/r6x3j6dwgt43do2/rubiks_pc_amd_t.png]With textures[/url]
Intel, [url=https://dl.dropbox.com/s/2cu68ra7zszencj/rubiks_pc_intel.png]both with and without textures[/url]
From this test, there seems to be a difference depending on the manufacturer of the GPU, though I can't say for sure this is the only reason.
Also, as a note about my previous posts, the laptop used here was also used in the previous tests, where it wouldn't render anything (its GPU drivers haven't been updated since then).
Has anybody encountered similar results with OpenGL?