my GPUs simply come up and report OFFLINE or DEAD, but going back to Scrypt seems to work fine.
Scrypt-N is more intensive and will tax your GPU to the max, chances are that your GPU settings are not stable enough so they keep crashing.
I converted to vertminer and they were all DEAD.
I then tried a bunch of setting changes, including removing almost everything and letting vertminer choose the defaults.
Still, everything comes up DEAD, even at intensity 8.
Switching back to Scrypt, everything runs fine again and I get good hashrates at intensity 20.
So, in summary, there is either a problem with how vertminer chooses default values, or with the scrypt-N running on certain brands/models of GPUs.
Then it's a RAM issue, how many and what GPUs are you running and how much RAM are you using?
I don't know if system ram comes into play, I thought all the work was done on the cards, which are attached via 1x powered risers.
However, if it does make a difference, each of my rigs (including the ones working correctly on VTC) have a single 4Gb stick.
Make one of the rigs 8GB RAM and it will magically work smooth
