okay after alot of intense oc learning i think i might be able to help you. if question is what are the speeds for your rams? try raising the multiplier up and increase voltage. if your cpu dont like that. then increase fsb speeds up and keep the multiplier at 18.5 like you have it. with this you will need to increase voltage. been seeing voltages for 4 + to be as high as 1.65. so you might just want to stick to 3.7 unless your going to oc just to hit high number cause at that voltage for long periods of time could effect the lifespan of your cpu. if you have any problems let me know ill see what i can do to help.
BTW what was your voltage on the 3.7
I had it stock at 1.4v, and the only way to get it stable around 4.0 was @ 1.5v, and atm I am not overclocking at all, 2 reasons behind it, I just built this and it's my second build, and long story short, the cooler I bought was a Xigametek Dark Knight, the fan burnt out after 7 days of use, so I am on the stock cooler until the replacement arrives. Reason two, because of my restricted budget on the rig, I skimped on the PSU, I bought a 480 watt PSU, when I built my rig, I went to a site that adds up the voltage by telling it the hard ware, my rig was going to run at 410-430, so I thought the PSU would have been fine, little did I know at the time, the PSU is junk, Link: http://www.newegg.com/Product/Product.aspx?Item=N82E168... I was told I should be using a PSU like this: http://www.newegg.com/Product/Product.aspx?Item=N82E168... so I gave my first build to a friend until he could afford to pay me back, when I receive that money I will start tweaking on it.