I don't think it is hardware specific.

Last week I was happily boxing using ISBoxer on 2 subscribed and accounts 3 trial accounts, after the latest Rift patch, my 2 subscribed accounts kept crashing after 15 mins but the trial accounts were fine.

My trials ran out so I upgraded them to subscribed accounts and now all 5 accounts crash within 60 seconds of each other after about 15 mins.

So i'm confused why my trial accounts were fine until I upgraded them. I made no hardware or driver changes, I just upgraded my accounts.

I have also found out that if around 13 or 14 mins you log out to the character select screen and then log straight back in again on all of your accounts then this seems to reset some sort of timer within rift and you are fine for another 13 or 14 mins, it's a pain but it's not as bad as all of your clients crashing.