My cousin has an iMac with a 512MB VRAM AMD Radeon HD 6770M. He is running Mtn Lion primarily and also has a Bootcamp partition for Windows 7.
When he runs Grand Theft Auto IV on his iMac in Windows 7, it claims that he has 1GB of VRAM, which he doesn't. There is a meter in the graphics settings in that game that shows you how much VRAM the settings will use and how much you have total. For example, it says "712MB / 1024MB used" or something along those lines with higher settings.
I thought it was just a faulty driver or something that's tricking the game, but when he applies settings that use more than 512MB of VRAM, the game runs just fine. The question of how this is happening has just been bugging us.
When he runs Grand Theft Auto IV on his iMac in Windows 7, it claims that he has 1GB of VRAM, which he doesn't. There is a meter in the graphics settings in that game that shows you how much VRAM the settings will use and how much you have total. For example, it says "712MB / 1024MB used" or something along those lines with higher settings.
I thought it was just a faulty driver or something that's tricking the game, but when he applies settings that use more than 512MB of VRAM, the game runs just fine. The question of how this is happening has just been bugging us.