These are difficult questions to answer. As you noted, the motherboard in your computer is customized and HP proprietary. The main concern with moving the motherboard to another case is the holes in the motherboard matching the stand-offs in the case. If they don't match perfectly it could cause a short that will fry it. Also, the front connectors on the board don't always match those in the case. You could choose a manufacturer and contact their Tech Support to see if they can help you determine if their case will be compatible with your motherboard.
I know that 80C seems a bit high, but the maximum for your CPU is 100C and the maximum for your video card is 89C.
Please click the Thumbs up + button if I have helped you and click Accept as Solution if your problem is solved.
I am not an HP Employee!!
Intelligence is God given. Wisdom is the sum of our mistakes!!
Be alert for scammers posting fake support phone numbers and/or email addresses on the community. If you think you have received a fake HP Support message, please report it to us by clicking on "Flag Post".