One embodiment of the present invention sets forth a technique for selecting a boot VGA adapter in a multiple VGA adapter system by controlling the system boot process using the VBIOS display detection service and boot flags that are stored in non-volatile platform memory. The SBIOS initiates a first boot that selects the motherboard integrated graphics processing unit (MGPU) as the boot VGA adapter. During this first boot, if the SBIOS determines that there are display devices attached to the MGPU, then the first boot completes normally. Otherwise, the SBIOS aborts the first boot and initiates a second boot that selects a secondary, discrete graphics processing unit GPU (DGPU) as the boot VGA adapter. During this second boot, if the SBIOS determines that there are display devices attached to the DGPU, then the second boot completes normally. Otherwise, the SBIOS aborts the second boot, and initiates and completes a third system boot that selects the MGPU as the boot VGA adapter while setting flags to ensure that the overall process does not repeat.