I have a Radeon 4850. Since it was heating up & making a ton of noise with the stock cooler, I decided to mount an Accelero S1. Operation went pretty smoothly, but on booting I had a nasty surprise: card was not outputting anything anymore. Did revert to stock cooler, but no luck -- no image, fan spinning at 100% and led D1601 always on. Looks like D1601 indicates overheating, but it's on from the second I turn my PC on despite heatsink being mounted properly.
Is my GPU fried, or did I mess up some sensor? Any way of resetting the card if it's a software issue?
I am having this same issue! I am really sorry to revive such an old thread, but this is an identical problem to mine. I tried to replace the fan on it, and then go back to the stock. Now I have a solid red light (D1601) with no video output.
No other system to test it in, sadly, and no on-board video to revert to.