At a 160 BCLK you can enable turbo. Most chips are still stable at 3.36 at stock voltage. Unless for some reason your cooling is inadequate. If your motherboard BIOS is the same as mine turbo needs the multi to be set to auto not 20.
here, this is what i did for my intel core i5 750 4ghz turbo boost overclock, unfortunately my ram wont go any higher than 1000 mhz for some reason but i was able to get my ram timings to 6-6-6-18@1N, btw here is my whole bios Screenshot, copy mine for your 4ghz turbo boost http://i357.photobucket.com/albums/oo15/skater44_04/myc...
I wouldn't use the XMP profile, you're better off just using manual. I did the following tweek:
- Profile on Manual
- Multiplier on auto
- Leave Turbo on
- Set BCLK to 160
- If you leave the RAM multiplier on auto it might choose a really low speed (Mine ended up at 960 MHz!), so manually choose 1600 MHz
I'd also highly recommend manually lowering VCore to about 1.25 V. If left on auto it surges to 1.38 V or so, which makes nothing but heat. I'm gonna test mine at 1.2 next, and then go down to 1.15 if possible. I can't adequately stress the difference this made, reducing voltage from auto to 1.25 reduced my full load temp by 8C. Looking forward to see how it does at 1.2.
We almost definitely have the same bios, so if you want I'll try to get you a screenshot. At such a conservative OC there's no reason to disable turbo boost. Do you have an aftermarket cooler?
My system is:
CPU: Intel i5-750
Motherboard: ASUS P7P-55D Pro
Video Card: eVGA GTX 460 1GB
RAM: Corsair XMS3-1600, 8 GB
OS Drive: Intel X25M, 80GB
Data Drive: Samsung HD103SJ
PSU: Antec Earthwatts 650
OS: Windows 7 Pro x64
Are you overclocking with the stock cooler ?
If yes , Download prime5 and stress the cpu for 8 min and upload a photo of the results to see the temp !!
Temp will help to determine the best overclocking you can and tell you the limit .