How to reset the sapphire vapor-x hd 4850 red light

[Guest]

Hello,
Have a Sapphire Vapor-X HD 4850 video card. It keeps "locking up", with screen going blank and red light on top of vid card. What's the problem, and is there a way to reset it without powering down my whole system?

 

[darkguset]

Have you connected the extra power cable?
This could also indicate an overheating problem