Motherboard not powering up HDD

Hard drives are usually connected to onboard a SATA or IDE port. If the port that hard drive is connected is disabled, hard drive will not be detected by the computer and you will get a message “hard drive not found”. Thus, when you meet the problem, you need to check BIOS setup.

 

This may help,
J Wick

Does the SATA power cable inside your computer have an orange wire going to it? I've heard reports that some drives, particularly those that were "shucked" from retail external drive enclosures, fail to spin up if they detect the 3.3 volts that the orange wire provides. Disconnecting that orange wire should allow the drive to spin up and work correctly. Your external reader likely doesn't utilize the 3.3 volt rail, and thus is the reason why you have no issues using the drive externally.

One workaround without excessive modification and assuming that your computer's power supply has a traditional molex connector, is to purchase a male molex to female SATA power adapter, which doesn't make use of the 3.3 volt rail at all. If you don't have a molex power connector, you can, in addition to the previous mentioned adapter, also purchase a female molex to male SATA power adapter, and combine the two together, which will essentially eliminate the 3.3 volt rail without cutting or removing the wire from the power supply.

Another option would be to purchase an inexpensive SATA "Y" power splitter and simply snip off the orange wire on the one side, so that this modification isn't done directly to the power supply's wiring and can be easily reversed if needed.

Thank you - this is something I shall try. I have been extremely frustrated trying to source a replacment power supply that none appear to have the 4pin ATX +6 pin PCI-e motherboard connectors - all those with 6 pin connector appear to be designed for GPUs rather than motherboards. It feels rather protectionist, as if Dell have designed a custom motherboard and PSU, with no access to replacement parts when they fail!