Originally Posted by djustiz
A bit late to the party it seems :-)
Interesting thread. Good read :-D
Just wanted to participate.
After a lot of fiddling, trial and error with things like 1usmus powerplan, undervolting, overvolting, PBO and per ccx tuning, I've settled for a rather conservative per ccx of 43/43/42/42 at 1.2V thats droops to 1.181V in cb20, and 1.175V in more extreme scenarios (Based on my chips FIT). This puts me just above a 10K score in Cinebench r20. It runs nice, cool and quiet. Around 30c idle, and 78c under torture loads with a single push/pull 240 AIO and very quiet fan settings, and is a very nice bump in performance over my 9000-ish cb20 scores stock.
Just be aware that I also had a very similar overclock for a while, at those kinds of voltages. It's deceptively stable. As in - it's not stable.
It'll push through cinebench and things, but chuck on a y-cruncher or prime95 load and it'll crash out. Run an extended blender run and it'll do the same.
That is, unless you have a really, really good chip. Like, made from gold pressed latinum and blessed by the grand negus himself, kind of chip.
Only 50% of chips will hit 4.1ghz all core, at 1.187v (under load, that voltage is).
Only 20% of chips will hit 4.15ghz, at 1.2v.
Yours is 4.2ghz, so you can extrapolate that down to something like 5% of chips (at best, probably less), at 1.225v maybe. Probably more like 1.25v, as the required voltages increase significantly at those levels.
I'm currently running a series of proper stress tests on mine, and it's currently a choice between -
4300/4250/4100/4075 at 1.225v under load
or 4400/4300/4200/4225 at 1.25v under load.
And I suspect I have an above average chip. A lot of people seem to need 1.265v+ in order to get stable above 4.3mhz.
Unless, of course, your chip really is that good. Then you're very lucky!
Also - Your FIT seems very low. Far as I'm aware, it should be more like 1.25v. or so, maybe even closer to 1.3v. What cooler are you using? You can't find out your FIT limits if your chip is overwhelming your cooler (which is why I'm in the process of upgrading my cooler). Once temps start rising the chip will drop voltages and throttle itself by default.