Ok whats up with my screen when i turn on my computer it works fine up to 50 sec then it goes blank whats up?

1. you have a dying GPU. 2. you have a dying PSU 3. you have a dying CPU. without any other details that about the best you can expect. Do the hard drives still operate? are the lights on the case still on? do you have an on board graphics adapter or is it a card? EDIT typically when you have the resolution set too high you get an 'out of range' display. Boot into safe mode to the generic VGA driver and see if it still goes black. Also did you upgrade the GPU recently and did not check the output of the PSU. you could have an underpowered system...

When you're trying to get help with a computer problem, you need to be as descriptive as possible. Saying "my computer runs fine for 50 seconds then it goes blank" doesn't help much. You need to tell people what kind of computer it is, what operating system you're using, how long it's been doing this, etc. Try posting your question again with this information so people trying to help you know what's going on. Without more information, it's impossible to say what might be the problem.