E8500 - beginner needs a few advices

here is my configuration:

Gigabyte GA-P35-S3G
C2D E8500 (more details in attached CPUZ screenshot) + Cooler Master Hyper 212 Plus
4GB DDR2 (2x2GB OCZ Gold 800mHz, 5-5-5-18)
Gainward HD4850 512MB GDDR3
WD Caviar Blue 640GB (6400AAKS)
PSU Sharkoon SHA450-8P 450W
Xigmatek Asgard Case (preinstalled 120mm fan on the front, xilence red wing 120mm in the back)


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i bought hyper 212+ a few days ago, and idle temperatures are literally always 37c.
i measured them A LOT of times with various programs (everest, realtemp, speedfan), and they never change, constant 37c.
however, load temperatures seem really good, after one hour of testing with orthos temperature was always around 45c.

now, to the point.
i want to try overclocking my cpu. i'm a total beginner so i red a lot of tutorials. basically i understand how OC works,
but there are still a few things i hope you will help me understand.
first, here are screenshots of my bios.


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so, i know that i should disable EIST and C1E in Advanced BIOS Features menu (done) and fix my PCI frequency @ 100mHz in M.I.T. (done).
after that i enable CPU Host Clock Control and raise CPU Host Frequency until my computer refuses to boot, which should mean it needs more volts.
so i should raise the voltage. but which one of these?
and i don't have a clue what should i do with my RAM? i red that you have to OC it too in order to reach 4gHz.

any other advice will be greatly appreciated.