Keep the box for your case and for your GPU. Pack those two items in their boxes. RAM/PSU/etc should be fine being stuck on the motherboard in the case. If you got a mechanical HDD, might be worth taking that out as well. And like someone else said, anything heavy should come out of the case. Be smart about the placement in the truck as well, put clothes/blankets/pillows under and around the case.
All this time we thought he was running and hiding but he wasn’t running, nor hiding. He was searching and he finally found her. Waldina is the reason Waldo isn’t hiding anymore.