Hi I have an early 2008 Mac Pro and for the last couple of months my monitor hasn't always been picking up a signal when I boot up my Mac Pro. Usually I'd just power off and restart and it would eventually work. However, it's not working at all now. Is it safe to assume that this a graphics card issue and it needs replacing or are there any other likely causes? I'd just like to eliminate any other causes before I go and buy a new card and it turns out that wasn't the issue. It's not the monitor, I've checked it on another machine and it works fine. Thanks.