What components are in the system, and what case are you using (and any fans)
The bricks sound like the gpu becoming unstable from overheating, 105C is at the limit where it throttles and ultimately shuts down/hangs.
Are these overclocked at all? How much room between the two cards? Single slot coolers or dual slot?
Check the fans are spinning and no dust is blocking airflow and if there is, you can use cans of compressed air which is usually best for removing dust from inside the case or components.
Is wire management good in the case?