Question : Problem: Monitor going to sleep mode with particular laptop

has 2 HP laptops A & B same model. has 2 HP external LCDs monitors A & B. Laptop A when connect to monitor A always has this intermittent of monitor A going to sleep mode. Laptop A when connect to monitor B no such issues. Laptop B when connects to either monitor A or B no such issues too.
Quite puzzling what's the cause of the issue between laptop A and monitor A

Answer : Problem: Monitor going to sleep mode with particular laptop

ended up changing the motherboard. appears to be on board video issue