Want to OC my Core i5 2500K for the first time, stay at stock voltage

[neosapien]

I bought a Core i5 2500K and Asus P8P67 Pro back in February of 2011 and never got around to overclocking it. I'd like to finally give that a try, but it would be nice if I could keep the power saving features active so that it would downclock/downvolt when idle, as usual. I'd just like to see how high I can OC it on stock voltage. My HSF is probably a Hyper 212.

Is this an option? Can I just turn up the turbo multiplier while keeping voltage at stock and power saving options enabled, so that the CPU doesn't chew up considerably more energy when idle? The last time I OCed a CPU was a Q6600-B3.

I've heard that the simplest way to OC it would be to simply set the Turbo multiplier to something like 42, for 4.2ghz, and leave the voltage on Auto, but then that might give it too much voltage and reduce the lifespan of the CPU.

 

[master_shake_]

set all cores to 40 and leave all the power saving stuff on.

stock voltage should be able to hit 4 ghz.

 

[Charlie98]

I actually have both of my 2500K's undervolted... on my desktop PC, it was the only way to control heat... but in the end it works very well. I would probably lock your voltage settings... I don't remember what I did on my Asus board, but I can pull it up if you are interested.

Do not use any sort of software to OC your chip, adjust the multiplier only... and don't fool with the backclock settings.

 

[Yuriman]

How things are presented in your bios will vary, but this is probably what you ought to do:

Change voltage to "Offset" from "Auto", set offset to either "0", or if that's not available, "+.005v" or "-.005v".

Change turbo multipliers to whatever you can get away with. This will likely be between 40x and 45x.

Disable C3, C6 and Package C States if you get random BSODs at idle/low load. This will have a negligible impact on power usage. You might also want to disable "Spread Spectrum".

You might need to increase your CPU's maximum allowed current. This might be presented in amps or watts. If left alone, your motherboard might throttle your CPU to stay within its rated TDP.

 

[neosapien]

Okay, I went into my BIOS and snapped pictures of all the screens that relate to overclocking that I'm aware of. After that, I updated my BIOS to the latest version, 3602, and re-shot the bottom of the AI Tweaker page with the new BIOS. All the other screens remained pretty much the same with the new BIOS.

Under the new BIOS, my CPU voltage is reported as 1.14V or thereabouts.

So if I understand correctly, I should make these changes, in order to overclock up to the highest level my stock voltage will allow:

Keep voltage at "Offset Mode". set offset to either "0", or if that's not available, "+.005v" or "-.005v".

Change turbo multipliers to as high as they will go with the system remaining stable. I presume by changing the Turbo Ratio away from Auto.

If I get random BSODs at idle/low load, disable C3/C6/Package C States/Spread Spectrum. Wait, which one is Package C states? Also, I use Hibernate. Would that be affected?

I don't see where to increase my CPU's maximum allowed current.

Charlie98, how does one lock one's voltage settings?

 

[Yuriman]

-From what I can see, you can overclock either by changing the CPU Ratio or Turbo Ratio. There shouldn't be any significant difference either way, but I'd try Turbo Ratio first.

-CPU voltage in offset mode = good, but change the CPU offset voltage to a value (like 0v, or 0.005v, something small), rather than Auto, because your motherboard may decide to start ramping up voltage by itself when you increase clocks. I don't trust anything that says "auto". Don't be surprised that the voltage WILL increase a little as you increase clocks anyway. This is normal.

-CPU Spread Spectrum -> good idea to disable it, this allows for clockspeed to wander a bit and can cause instability, but you might be able to get away with leaving it on.

-C3 and C6 you might get away with leaving on, doesn't look like you have an option for package C-states, but can cause instability. Disabling these should not affect hibernation or power consumption.

-CPU PLL voltage (which you have highlighted) should probably be left alone. Some people reduce this to cut back on heat. My system is perfectly happy with a PLL voltage of around 1.5v, but it's unnecessary to mess with.

-Under CPU Power Management, you see the "Turbo Mode Parameters". These are your CPU Current limiters. "Long Duration Power Limit", "Short Duration Power Limit" and "Primary Plane Current Limit" can be increased if you find your CPU is not going up to the clockspeed you've set. I generally set mine to "500" (amps), or some other similarly large value. I'd also change "Additional Turbo Voltage" to 0, or whatever small value you can put in, to make sure your board doesn't automatically add voltage.

 

[Charlie98]

-CPU voltage in offset mode = good, but change the CPU offset voltage to a value (like 0v, or 0.005v, something small), rather than Auto, because your motherboard may decide to start ramping up voltage by itself when you increase clocks. I don't trust anything that says "auto". Don't be surprised that the voltage WILL increase a little as you increase clocks anyway. This is normal.

-C3 and C6 you might get away with leaving on, doesn't look like you have an option for package C-states, but can cause instability. Disabling these should not affect hibernation or power consumption.

OP, voltage offset mode is what I meant by locking your voltage... It's been a while since I've been into the BIOS to tinker. FWIW, my 2500K/Asus combo is set at 4.3GHz and is completely stable, so I don't feel the need to 'fix' what isn't broken.

Turning off one of the C-states makes the CPU run at 100%, so use CPUz or another utility to watch your CPU after making changes.

I keep my OC's simple-stupid... let me go up and see what I've done with mine...

EDIT: One of the things I didn't care for was the sheer amount of adjustments you could make on the ASUS board... the problem is the manual did a very poor job of explaining each of the functions... which is probably why I left many of the settings alone.

I'm running BIOS 3603, so there may be some differences...

In Extreme Tweaker tab...

AI OC Tuner set to manual
PLL Voltage I left on auto
CPU voltage I set at 1.260v (undervolted, I believe, but I don't remember exactly.)
Spread Spectrum is disabled.

In Advanced tab...

My CPU multiplier is set at 43

My memory bclk is set at 100.1 (I would not go any higher than that... Sandy and newer don't respond well to backclock changes, or that has been my experience.)

Speed step is enabled

All my C-states are still enabled.

 

[neosapien]

Okay, I tried setting Turbo to 40x then running LinX 5 passes. Holy crap, power usage skyrocketed, and my core voltage went all the way up to 1.37v in Core Temp. Somehow the motherboard is still tapping into some extra voltage when I try and OC it. I'll take screens of my latest BIOS config to show you where I'm at. link

11/30/2015, Stock Settings, 20 passes:
CoreTemp 79w max, 58/63/63/62c max, 1.27v CPU VID in Core Temp 1.0 RC6 @ load, CPU-Z 1.16-1.2v

12/1/2015, Turbo 40x, aborted before 1 pass:
CoreTemp 108w max, 69/75/76/75 max, 1.37v CPU VID in Core Temp 1.0 RC6 @ load, 1.27V Core Voltage in CPU-Z

 

[Borealis7]

my 2500K @ 4.4 stock volts is game stable, and IBT stable, i do have rare crashes but that may also be my ageing video card .

 

[Yuriman]

Voltage will go up because the CPU has a voltage table of what voltages to be used at what clocks. You could try a negative offset; I actually use -0.090v on my 3570K @ 4.0ghz. YMMV.

 

[neosapien]

Borealis7, What does Core Temp show that your VID, Power usage, and max temp are at full load (in LinX) on your 2500K that is @ 4.4 with stock volts? And what does CPU-Z show for your Core Voltage?

Yuriman, okay, I'll try the negative offset next. But wouldn't that negative offset also apply even when at idle?

 

[Charlie98]

Yuriman, okay, I'll try the negative offset next. But wouldn't that negative offset also apply even when at idle?

It will. In reality, your CPU doesn't even need all that stock voltage at idle.

Your core temps are not that bad, even considering the OC... it's better than my original 2500K that topped 90C at 4.1GHz in LinX... that's how I figured out undervolting would reduce heat.

EDIT: Using CPUz as a monitor, my Core voltage doesn't change... it sets idle at 1.256v and runs at 100% in LinX at 1.256v... hmmm.

 

[Yuriman]

Yeah, it will apply at idle and partial load. If you have an "additional turbo voltage" option, you could try a negative there instead, but I'm able to get away with as much as a -0.13v negative offset on my chip; I run -0.09 for some safety margin.

 

[Ranulf]

Couple of threads on overclock.net for 2500k/sandy bridge:

http://www.overclock.net/t/1100100/info-intel-2500k-2600k-overclocking-tips

Asrock mobo version:
http://www.overclock.net/t/1198504/...-guide-sandy-bridge-ivy-bridge-asrock-edition

 

[neosapien]

That guide looks excellent. I read it, and then applied the settings it lists in the guide. I got up to 41x turbo multiplier at manual 1.2v, then got a BSOD 0x101, then retried with 40x turbo multiplier, and was stable at Prime 95 Custom 1344 15 minutes, then Custom 1792 15 minutes, reaching 58/61/60/60c max in Realtemp and drawing 83 watts. CPU-Z says I was using 1.192v. Then I did LinX 20 passes, my CPU was drawing 107 watts, reached 66/71/73/70c, RealTemp says that the VID was 1.3661v.

So now I know that I'm stable at 40x turbo multiplier at 1.2v, even when the CPU is calling for 1.3661v. So do I change my voltage from manual 1.2v to offset -0.1661v? How many watts does a Core i5 2500k tend to use if it's at a static clock of 1.2v when idle, and how many when it's able to downvolt when idle?

Update: I went down, step by step, to offset voltage -0.090v, which is still stable, but the cpu goes up to 1.264v during load, instead of 1.2v. LinX temps are 72/79/80/78c. Don't know if it's inadvisable to continue stepping down.

 

[BonzaiDuck]

I can't resist posting a brief footnote to this. I couldn't guess how many threads like this one have been posted on the forum since two years or so after the initial chip releases with the P67 chipset.

I gathered a lot of information from P67 SB overclocking guides -- no less with guides for Z68 or Z77. My systems use the Z68 and updated "Gen3" chipset, the latter supposedly ready-to-go for an IB chip.

Yuriman has it for a good summary about fine-tuning these processors.

I would only suggest the following:

Initially set the Offset voltage to 0 or +0.005V. There is an interaction between Offset and LLC (load-level calibration) if you use the latter, such that a negative offset value may cause the idle voltage to drop too low.

I'm not confident that an ASUS P67 board would have this feature, but the P8Z68-V Pro board bios had a voltage setting called "Extra voltage for turbo." If you had this feature and used it, you wouldn't need to touch the initial Offset voltage (+0.005V) at all, or adjustments might mean only another 0.005V increase to 0.010V. They just didn't do a good job integrating that feature in the BIOS menus: it was buried in a "power management" menu item.

The C3/C6 "report" feature enables "hybrid sleep state," which you do not need to make the computer sleep and wake reliably. But enabling it WILL (as Yuriman says) cause random, intermittent idle-speed (with EIST) crashes, freezes or BSODs. These can happen so infrequently they can be hard to troubleshoot without input from those of us who discovered it: my crashes took place over intervals of 7 days to 1 month.

So you don't need to enable C3/C6 at all. Disabling it will still allow you to sleep the computer, and it will still allow you to hibernate the computer.

Traditionally, we were always advised to disable Spread Spectrum for overclocking. This may be a good idea for the exercise of finding the highest stable overclock setting, but for whatever overclock you choose, you'd do no harm to re-enable Spread Spectrum, run your stress test again, and make any minor voltage tweaks necessary.

In my case, for two machines (2600K and 2700K) I didn't have to adjust anything with re-enabled Spread Spectrum. But the skinny on the street and my own experience suggests that enabled Spread Spectrum will actually stabilize idle (with EIST) voltage or reduce the variation of it: idle voltage becomes more stable.

 

[neosapien]

Thank you BonzaiDuck, I deactivated C3/C6 report, and ensured that Spread Sprectrum is still activated.

I am not sure that I should set the offset from -0.090v back to 0v, because then my load core voltage would get too high and my temps would be very high. I find that with offset at -0.090v, during idle mode the core voltage drops to around 0.888v. I left the PC alone to idle for around 6 hours or so, to see if it idling at that low voltage would cause it to BSOD, and it didn't, thank goodness.

I have the Additional Turbo Voltage setting on my P8P67 Pro, but it only goes positive, so I'm not sure how I could use it to achieve my goal of having voltage that's around 0.9v at idle and 1.2v at turbo full load, both of which I've found were stable. Do you know if there's some way to do that? Because right now, with -0.090v offset, I'm at 0.888v idle and 1.264v turbo max load, and I'd love to be able to bring that 1.264v down to 1.2v while still being able to undervolt while idle.

Edit~I experimented with setting Addl Turbo Voltage to 0.020v while in Manual 1.2v mode, and it had no effect, Core Voltage remained at ~1.2v during Turbo mode with LinX.
I then experimented again with Offset mode and Addl Turbo Voltage, setting Offset to -0.005v and Addl Turbo to 0.004v (I believe). During Turbo, Core Voltage jumped up to 1.344v, way too high.
I then reset Offset to -0.090v and Addl Turbo to 0.004v, and Core Voltage was around 1.256v during load.
I then reset Offset to +0.005v and Addl Turbo to 0.004v, and Core Voltage was around 1.344v during load.

Also, I used a Kill-a-Watt to measure the wattage for both offset -0.090v mode and manual 1.2v mode. Here's what I found:

Offset -0.090v mode, Turbo 40x:
95w total system power consumption during idle
210w total system power consumption during LinX

Manual 1.2v mode, Turbo 40x:
102w total system power consumption during idle
190w total system power consumption during LinX

It would be great to get that to 95w idle, 190w load. But if I can't do that, then the manual setting would seem preferable, wouldn't it? 20w less during load means less opportunity for overheating, even if it's at the expense of +7w during idle. Unless shooting 1.2v into the CPU at all times would reduce its life expectancy, in which case it's not a better bargain.