This Dell Precision M6600 model does not show a display during startup unless it is connected to a power source.
This Dell Precision M6600 model does not show a display during startup unless it is connected to a power source.
This problem has been ongoing for a while. I don't recall exactly when it began. On a cold start with the AC adapter plugged in, the machine boots into Windows normally and displays a screen backlight without graphics. When using only the battery, it still boots correctly. If I connect the adapter as soon as the first error appears on the screen, everything seems fine. It seems like a power issue from the adapter or a power management problem, but I've tested the Dell 240W charger at 200W—it maintains 19.75V and is stable, so I don't think the charger is the cause. The BIOS correctly identifies the charger as 240W.
I currently have the A12 bios, which is outdated and requires an update. If my reboots are unstable, it could be dangerous. If a bios update might resolve this, I'll try to figure it out.
I already have the A12 bios, though it's outdated, and a reboot might be unstable—updating could help. If the update succeeds, everything should work fine.
On the other hand, consider disassembling the laptop (after unplugging it), remove the internal battery, RAM modules, and then hold the power button for 30 seconds while the RAM is off. Clean the contacts of the RAM sticks with an eraser, removing any residue, and reinsert them. Try starting without the battery and see if the problem persists. If it does, attempt a reboot, then power down, disconnect from the wall, and reconnect the battery.
So...I performed the deep Dell diagnostic on memory, drives, etc., after about an hour. It didn’t detect anything wrong. But I suspect there might be something related to the integrated video during boot. This machine has "Optimus," which seems to handle switching between the integrated GPU and the discrete GPU. In the BIOS, you can disable Optimus, which I think should only affect the discrete GPU for video. I’ve noticed that once I set it, save, and exit the BIOS, the machine will boot with full video support. However, if I try it again after a full shutdown, I won’t see video when it’s plugged in. Restarting brings me back to the BIOS where Optimus is off.
It’s unusual behavior, and I’m aware there were problems reported by other Dell users.
I wonder if the BIOS might be checking certain drivers during boot that could cause issues? Or would a BIOS package include all of those components?
The difference in boot behavior between plugged in and not is quite strange. AI tends to assume there’s an adapter power rail problem, but I’d need a schematic to fully understand the situation.