Hey sorry the Asus cards ended up not working out for you man.
Lot's of good general information here in the 580 OC thread
. But generally first you want to make sure you are on the latest MSI AB 2.2.0 beta
, then in settings, general, "unlock voltage control" and "unlock voltage monitoring", then in the monitoring tab, in the middle of the page under "active hardware monitoring graphs", scroll down to the bottom and check "GPU voltage" and I'd also recommend checking "VRM temperature" and "Memory temperature". Then after it will ask you to restart (I think) go and put your GPU under load and check the graph for your GPU voltage to see what your stock voltage is. From there you would use the voltage offset to determine what you want your voltage to be. Say for example your stock voltage is 1.025v under load, then a +75mV would bring you to 1.1v etc.
That should help you understand the way your voltage adjustment works. As for safe voltage limits unless you have drastically
lowered the fan profile from it's stock curve then going straight to 1.1v will be no problem for the Lightning. From there I would gradually and incrementally increase both your core speed and the core voltage (I don't use or advise others to use the Memory or PLL/AUX overvoltage mostly because they aren't necessary but also because I don't know the safe limits for those) as needed while testing in an appropriate stress test. My favorite is Unigine Heaven
for about 15 minutes in between incremental increases and 30-45 minutes as a more final stability test once you think you're stable. In Unigine watch for rays of colored light as signs as instability, they look like sun rays but independent of the sun and in any color, as well as more typical signs of instability such as the program, your drivers or your core clocks crashing. Watch your temps as you incrementally increase the core clocks and voltage and until you get pretty comfortable with the limits of what to expect from your card and what it can do I would stop at 1.15v which is a good balance between a high level of safety and still plenty of room to OC from where you stand now.
Good luck, have fun, and I would post any further questions in the 580 OC thread linked above, but what I've given you here should get you off to a good start.Edited by juano - 10/18/11 at 4:48pm