Just upgraded to a system based around an Intel i5, a Gigabyte GA-P55M-UD2, and 4Gb (2 x 2Gb) of 1600 9-9-9-24 Corsair XMS3 memory. At the current time, I have my BCLK at 185 and my multiplier at X21 for a total speed of 3.885 Ghz. I currently have my VCore at 1.375v, my VTT (QPI) at 1.37v, my PLL at 1.80, and my vDimm at 1.65v. My plan was to go at least 200 on the BCLK and to back off on the multiplier to 20, while turning off Speedstep (EIST), Tubo Mode, C1E, and C-States, giving me a stable 4.0 Ghz. I am using a very good CoolerMaster CPU cooler (cpu heat is not a problem) and (CoolerMaster) power supply (550 watt - with a meter that barely reads 200 watts at full load).However, no mater what I try, I can't get my system stable if I go past 185 BCLK. Is that because of my 1600 speed memory? Do I need to upgrade to good 2000 speed memory to enable me to go to 200 BCLK to give me at least 4Ghz CPU speed?Thanks,RH

Just upgraded to a system based around an Intel i5, a Gigabyte GA-P55M-UD2, and 4Gb (2 x 2Gb) of 1600 9-9-9-24 Corsair XMS3 memory. At the current time, I have my BCLK at 185 and my multiplier at X21 for a total speed of 3.885 Ghz. I currently have my VCore at 1.375v, my VTT (QPI) at 1.37v, my PLL at 1.80, and my vDimm at 1.65v. My plan was to go at least 200 on the BCLK and to back off on the multiplier to 20, while turning off Speedstep (EIST), Tubo Mode, C1E, and C-States, giving me a stable 4.0 Ghz. I am using a very good CoolerMaster CPU cooler (cpu heat is not a problem) and (CoolerMaster) power supply (550 watt - with a meter that barely reads 200 watts at full load).However, no mater what I try, I can't get my system stable if I go past 185 BCLK. Is that because of my 1600 speed memory? Do I need to upgrade to good 2000 speed memory to enable me to go to 200 BCLK to give me at least 4Ghz CPU speed?Thanks,RH

What have you got the memory multiplier set to? If you've still got it at x10, then it's no wonder your RAM won't make the trip, because it's at 1850 MHz already. Try dropping it to x8 and see if you can go up from there.RegardsBob ScottColonel, USAF (ret)ATP IMEL Gulfstream II-III-IV-VColorado Springs, CO

I am not sure how that works. If I drop the memory multiplier to 8, then wouldn't the fact that I am limited to x21 on the CPU multiplier hold me back? Please excuse my ignorance, but please explain how the memory multiplier works. It's the first that I have heard if it.Thanks,RH

The memory multiplier is precisely what it sounds like. It determines the RAM frequency by multiplying itself times the bclk. Example: bclk 185x10 = RAM @ 1.85GHz, well outside of what your RAM is rated at. If you drop this number to 8, the resulting RAM speed would be 1.48GHz, which is within specifications.

The memory multiplier is precisely what it sounds like. It determines the RAM frequency by multiplying itself times the bclk. Example: bclk 185x10 = RAM @ 1.85GHz, well outside of what your RAM is rated at. If you drop this number to 8, the resulting RAM speed would be 1.48GHz, which is within specifications.

But because the CPU multiplier for the i5 is locked at x21, if I reduced the RAM multiplier to x8 my total CPU speed would drop from the current 3.385 Ghz to 3.108 Ghz. So, I guess the answer to my original question is that my current 1600 speed RAM is holding me back, and if I want to get to 4Ghz or above like many others have done with the i5, I am going to have to cough up some $ for some good 2000 speed RAM. Is what I am saying true? Thanks in advance for your response.RH

No. Your CPU multiplier and memory multiplier are two disparate entities.

I appreciate the response TechguyMacCIf I lower my RAM number to 8 (resulting RAM speed being 1.48GHz -- within specifications), can I then move my BCLK to 200 for an i5 overclock of 4Ghz with a CPU x of 20?Thanks,RH

Won't know until you try, but I'd lean towards the answer being yes, providing your voltage settings are adequate.

I will give it a try, thanks.RH

excuse a noob but what is wroung with uping your BLCK and leaving the ram stuff on AUto, would'nt the ram just auto to match your cpu clock, assuming the ram you got is rated fast enough.

What is wrong is precisely what you see described here. If you don't lower the memory multi, it will be left at stock and will soon surpass the capability of your RAM.

What is wrong is precisely what you see described here. If you don't lower the memory multi, it will be left at stock and will soon surpass the capability of your RAM.

Ok thanks for the OC lesson, excuse me while i return to Bios

Thanks guys for your input.Wouldn't I get much better results from just going ahead and buying some good 2000 speed memory and leaving the memory multi where it is while being able to up the BCLK to 200 or more. Or, would it be a waste of money. I as just used to thinking that the BCLK should match memory speed. RH

You could try, but I wouldn't. Recently all the really high speed DDR3 products were discontinued or recalled due to design/manufacturing issues.

You could try, but I wouldn't. Recently all the really high speed DDR3 products were discontinued or recalled due to design/manufacturing issues.

That was true more than six months ago but has all been resolved, You can find plenty of 2000+ on NewEgg. The only good reason to grab some is that it allows you to do very low latency at very low voltage. 7-7-7-20 on 1.5v at 1600+ helps keep the IMC cool and allow for higher O/C without stress.