Why would I wanna do that? Help you that is (snicker) ... check the top of the rumble standings.
XTU does weight voltage along with benchmark performance -- same completion time at lower volts gets a higher score. It also rewards memory efficiency. The first suggestion is to read through the RAM adjustment parts of the overclocking guides on the ROG site.
Removing unneeded processes and services from windows is certainly effective and legal. So is raising the priority of the PerfTune.exe process. Try it at Realtime priority.
If your CPU is shakey at 4.4GHz with 1.275 volts, it could still be better than my dog. Mine needs 1.30v to be OCCT stable at 4.4GHz. Getting to higher clock speed means being able to take the heat. Those posts above that talk about heat are getting right to the point.
Your cooling is doing fairly well for AOI water. The big hurdle for cooling a Haswell is inside little darlin' -- Intel left a lot of space between the lid and the silicon, then filled that space with a so-so TIM. All the water in the world won't get that chip cool if the heat has to go through that TIM. Hence delidding. That's a touchy job, a risk, voids the warranty, etc. and isn't for the faint of heart.
I'm crazy two ways for the following. One for doing it at all. Two for telling the competition, but you could see most of it in my XTU profile. I set my dog to a core multiplier of 47, cache multiplier 45 and then run BCLK up until the screen turns blue in XTU. One step less BCLK is fine for that benchmark. I run XTU at 4747MHz, but not everyday use. Oh, by the way, that takes 1.565 Vcore ( ! ) and peaks the temperature at 83C even with the delidding.
Still wanna go for it?
Jeff