Here's a real good thread to help refresh your memory http://www.overclock.net/amd-general...ing-guide.html
it has a lot of good info, plus gives you a path to follow.
For a 3.9 try starting low, maybe 1.37v and run ITB, if you get a BSOD raise the Vcore a couple bumps. Repeat, till you can pass 5-10 runs. Than go for a 4.0GHz. From what I've seen many can reach 4.0 with only 1.38-1.41v depending on ambient (mine would run at 1.4 with a Scythe Mugen). The whole idea is to use a minimum voltage increase to keep the temps down.
Once it passes ITB than try a 12 hr run of prime95 on "Blend". After that you could try using the ref clock at 250MHz and CPU multiplier of 16x for a 4.0GHz but you'll need to study the link above for more details on how to do this.
Work with only one area at a time. 1st CPU by itself, than 2nd, Ref Clock. Combined the two (and stabilize) and than 3rd, work in a nice 3000MHz NB Freq (stabilize), and finally 4th raise the dram freq. At this point you'll want to be able to pass 24 hrs of prime95.
In the end these would be a reference only (your settings may differ slightly)
250MHz x 16x = 4.0GHz with 1.38-1.41v Vcore (max Vcore is 1.55v)
3000MHz NB Freq with 1.35 to 1.4v for CPU/NB voltage (Max CPU/NB voltage is also 1.55v)
2000HT Link Speed +/- 100MHz with HT voltage at stock/auto
1672MHz Dram Freq (assuming you have 1600MHz Dram)with timings manually entered along with stock Dram voltage (which you may need to increase slightly, Make increases of .05v till stable) also manually entered.
Be sure to have CPU Load Line Calibration on full (same with CPU/NB LLC).
Disable Turbo Core and any OC Utility options.
And if you use "Offset Voltage" instead of "Manual" you'll still have the option to enable Cool & Quite.
When testing with prime95,
A BSOD usually means a lack of Vcore,
If you get a "Worker Has Failed" error this is usually a lack of Dram Voltage or CPU/NB Voltage.
If you'd like/need any help feel free to PM me. (I also have a list of settings to help setup the bios if you need help with that).Edited by The Sandman - 6/4/11 at 11:13pm