Maybe not specifically a vixen question, but not sure where else to ask.

My desk top that i am using to sequence does not seem to match up. for example, i have a pulse set up for each drum beat. I have the marks set, so the timing is correct, however, during each playback the lights are off a little different each time. I moved to the laptop i use at work to sequence and it keeps up just fine. I am only running 8gb memory on the desktop, laptop is 12gb. Desktop has AMD 4300 quad core processor 3.8 GHz. Desktop has NVidia GeForce GT710 graphics card.

Any ideas or suggestions?