you should look in to why these miners die after x amount of hours
I haven't had problems with mine going down on my Windows 7 box at all. The speed isn't what I expected out of them though.
You're not getting the 70kh/s each? I have 30 with no issues on any of them.
Silly mistake, my batch file had 400 in it instead of 800... so it was ramped down. I just copied the syntax for the LTC_ONLY they included in the bundled software. All is good now. I normally use BFGMiner so I didn't know any better.
Glad to hear you're up and running at full speed.