elsupreme The USB sticks aren't the only thing you need to consider when trying to adjust amperage.  Your USB hub and what each port can provide voltage and amperage wise is also very important.  I have the Bitcoin Merch 7 port one and I can tell you it's not great.  Just like others have said, it has power problems and each port is inconsistent.  Then not only what each port can handle, but how much they can handle when multiple ports are used.  For me, I can only achieve a stable 445Mhz @ roughly 2.4 - 2.5 amps per stick. I have found that each port resets at different max amp draw causing the plateau and this decreases with each USB stick plugged in with the first port drawing the most power and amps which takes away from each port as it gets farther away from the power source.   But this is why you should get a USB ampmeter so you can watch and tell at what max amperage does it plateau and from that, you can then tell your approx max freq you can use on that hub.   That is the most likely case of your issue unless you have one of those Gekkoscience hubs.  Hard to find at this point.

As for eyeballing to OC, good luck.  Each stick and USB port is different.  And even if you manage to get it to stop plateauing you'll most likely be either under volting so missing out on more hashrates or over volting drawing more power than needed for what the hashrate you are getting. 

But if you want somewhere to start, dial the voltage regulator so that the flat side of the dial is parallel to the side of the right side of stick (facing back of stick), this put it at approximately 2.3 - 2.4 amps and will easily run 400 mhz. Set your freq to 400 just to show you aren't plateauing.  If you are, your usb hub isn't able to supply enough power to do anything exciting or your sticks have gone bad (but i think that's less likely)  If it runs stable at 400 Mhz for 30 min, then stop the miner and change your freq to 450.  Start it back up and it will likely plateau again but at this point while it's running, you want to dial back the voltage by turning the dial counter clockwise ever so slightly after each time it plateau's until it stops.  It's fine to do while they are on, just be careful not to short your sticks.  If you try to increase the voltage by going clockwise, I can almost gaurantee it will go back to plateauing because as I mention, your USB hub is key in achieving those higher clock rates.   I had to go back to 445Mhz because while I was able to get to 450Mhz I was getting lower hash rates because the sticks weren't able to get the power they needed to go higher and If i tried to increase voltage at all it would start crashing.  On avg, i'm doing 295Gh/s per stick.