Most GPUs will have fan spin & lights if only on pcie power (the pcie slot provides 75W without external connection), but then misbehave during display; I know it sounds stupid but make sure the 12V power connector on the top of the card is firmly plugged in, that connector in particular has a reputation for being unreliable.
Most GPUs will have fan spin & lights if only on pcie power (the pcie slot provides 75W without external connection), but then misbehave during display; I know it sounds stupid but make sure the 12V power connector on the top of the card is firmly plugged in, that connector in particular has a reputation for being unreliable.