humanage

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Aug 11, 2010
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I have an Intel i5 2500k, MSI p67A-gd55 motherboard, and Ripjaws X F3 8gb 1333Mhz RAM. This is just minimum info. I'm water cooling and get 26c idling and get about 51c at full load. This is when I'm at 4.2GHz. What's the highest safe voltage I should use?

P.S. I want to know voltages for all of the ones I should raise. Main I need info on is core voltage.
 
Intel has verified (through their Sandy Bridge technical PDFs and online chats) that 1.52v is the max 'safe' vcore. As long as you can keep temps under control, you can go that high. Of course, keeping it lower than that would be a good idea, just in case...

Oh, and 1.9v PLL is required for stability with some of the higher overclocks. Don't go too much over that though.
 

So far just 4.8GHz with mine ... but I'm not done. I haven't even started playing with BCLK yet.

I'm actually aiming for 5.1GHz on air, so we'll see what happens.
 
*sigh* :fou: :pfff: :cry:

Sadly, I seem to have encountered this processor's multiplier wall. It's running at the absolute ragged edge of stability at the 50x multiplier, and no amount of voltage/setting stroking will allow for passing more than a couple hours of Prime95. And I didn't even attempt IntelBurnTest, which works the CPU harder by using most of my 12GB of RAM.

The 49x multiplier seems to be more cooperative in all ways, allowing for less voltage to help keep temps under control.

Once I do my stability testing (24 hours of Prime95 and 50 runs of IBT at Maximum), I'll start with the BCLK.

There's still (slim) hope for that 5.1GHz overclock yet ... all I have to do is hit 105MHz BCLK. :ouch:
 
Well ... it seems my hopes of a 5.1GHz or higher overclock have been defeated. My CPU's multiplier wall prevents anything higher than a 49x multiplier, and my mainboard's max VCCSA of 1.2v is preventing me from getting higher than 102MHz BCLK. Even that isn't totally stable.

I think I'm actually just going to go back to using the 100% totally stable Turbo 4.8GHz preset in the ASRock UEFI. All of those voltage increases aren't really worth the measly one multiplier bin gain. Plus I don't have to worry about temps. I'll probably be upgrading to Ivy Bridge or Sandy Bridge E, but I'd like to have this processor to fall back on just in case those plans don't pan out. I'll just have to be content with 4.8GHz for now...
 

And for reference, at stock speed (Turbo Boost enabled):

OpenGL (GPU): 54.74 FPS
Reference Match: 99.5%
Render (CPU): 5.42 points
Render (Single Core): 1.48 points
MP Ratio: 3.66x

Turbo Boost skewed the last two a bit, beings the CPU was running 300MHz faster on the Single Core test.

Some nice gains there, going from stock speed to 4.9GHz on a Sandy Bridge.
 

livetaswim06

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Feb 16, 2011
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I have to say I am at 4.4 happily with my 2500k. I did the auto-OC with the ASRock Extreme4 and left it alone. Idles around 30 C and at load with Prime95 is at 58 C or so. I use a Scythe Mugen 2 rev. B cooler with a Noctua NF-P12 as the heatsink cooler.
 

DurgeDriven

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Apr 1, 2011
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Hello

I used 1.375v in Bios allow for droop for 5GHz, ran stable all day.
Only thing stopped me from going higher was worrying.

My 24/7 normal running is 4.5Ghz @1.3v full load 1.28v idle
Only other voltage I touched was ram set @1.5v
Prime @4.5Ghz is 60c Ambient 20C
Disabled almost everything in bios
Cores I never touched or pll

Is 1.28v too high 24/7 ie: for not underclocking/undervolting ?

MSI P67A-GD55 (B3)
2500K
CM Hyper212+
2 x 2GB patriot signature 1600 9.9.9.28 ( spd not linked)
2 x Gigabyte GTX460 soc (815/4000)

Getting Noctua and 2x4GB GSkill 1600 1.5v this week.

Longtime AMD user, very happy indeed.



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edit; BTW genieOC sets the voltages way too high so i would watch other auto OCs as well.

At 4.2GHz Genie used more power then I did for 5GHz
 

DurgeDriven

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Apr 1, 2011
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Was only to see limits ( never had a bsod or freeze all the way )

I fully understand as I said 24/7 is 4.5GHz ;)
Poor air cooler for that overclock and at any rate.

I could wack H70 on it would be 5GHz maybe more 24/7 no worries but as you say the point ? ;)

4.5Ghz is my sweet spot.