Erratic Physics behaviour while testing in 2 computers

Hello I've been having some trouble testing a sorta prototype of my game in 2 different computers, in my house desktop it runs as it should (To be more specific my character moves with a rigidbody addforce( bla bla bla . forcemode.impulse) ) which I also use to aplly a jumping force, while grounded the movement and speed works fine but when jumping in my desktop it jumps as it should and in the other desktop it jumps like the triple of the heigh it should, the only difference bettwen both desktops its that one uses a EVGA GTX 560 non ti and the other a Saphire Radeon HD 6770, I was wondering if thats whats causing the erratic behaviour with the controls, also u have a trigger that plays the falling animation once supposed max heigh of the jump is reached when it jump to high theres a point where it plays the falling animation but is still going up.

Appreciate any help, Thanks.