2500k, overclocking and voltage?

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Gawd
Joined
Mar 9, 2000
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I'm just getting back into overclocking after a long hiatus. I can't even remember what the last CPU I overclocked was (a P4 on an Abit AI7 maybe?) Things have changed quite a bit since the last time I did this. It used to be locked multipliers and all FSB adjustments. No dynamic clocks, speedstep, or any of this fancy stuff. In any case, this is what I've got:

Maximus V Gene (MVG)
Intel i5 2500k
Coolermaster 212+ heatsink in a push/pull configuration

Right now I've got it humming along at 4.4ghz using automatic voltage. It's tearing through some prime95 small ffts as I right this. I've noticed that the voltage the CPU uses is gradually increasing as I bump up the clock speed. At 4.4ghz it is running at 1.336v. At 4.3 it was running at 1.316v. At 4.2 is was even lower. From what I've read, it is the CPU that is requesting the increased voltage, correct? Presumably, if I continue to increase the clock speed, the voltage will continue to scale up, yes?

I tinkered momentarily with Offset voltage mode, applying a -0.025 to my 4.4ghz overclock, in an attempt to bring it back down to 1.31ish but prime95 bombed as soon as it started up. Seems that automatic voltage, or a + offset is the way to go?
 
Yes as you increase your clock speed it will give it more voltage and at 4.4Ghz and 1.33v isn't bad for a auto voltage though, what are your temps in prim95? What is the idle and load voltage?

P.S. Don't declare it stable until a good 10hrs in Prime95
 
Prime95, with small ffts, is running 64c - 69c depending on the core as reported by HW Monitor. It ran overnight at 4.3ghz, so I moved it up this morning to 4.4 and I'll let it run for a while.

Full load voltage is 1.336v. Idle is something like 1.016v or so.
 
Do you have it downclock at idle? or straight 4.4Ghz? I wish I could do that low of voltage. Mine is stable at 1.37v for 4.5Ghz but maybe it's because I have HT enabled
 
The problem with auto voltage is it typically goes a step or two higher than it needs to. If you manually tune it, you could keep going!
 
At 1.33v~4.4Ghz~under 70c load I would not be worried a lick if it's stable.
 
I wouldn't either, but it doesn't mean he shouldn't try to drop a little voltage or push it a little higher on 1.33!
 
Thanks everyone. Since posting I've kicked it up for 4.5ghz, still using auto voltage. Its still sitting at 1.336v. I guess I should be more specific, the voltage in the bios is set to Manual and then Auto. I don't have a specific voltage dialed in, so I guess it's using whatever the VID is?
 
Check what the VID is saying when your at 4.5Ghz in either AIDA or another program that will read the VID but make sure you read the VID when the clock is actually at 4.5Ghz and not idle 1.6Ghz so if you have to stress test while checking the VID. The VID will change depending on what your clock speed is. My 2600K will read a VID of 1.39v at 4.5Ghz but it doesn't take that to be stable though, I'm curious to see what yours will say at the same clock speed as mine

VID= Suggested voltage by intel for a specific speed
CPU Voltage= What is currently running at
 
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Checked the VID with Core Temp, reads 1.3761v at 4.5ghz. Actual vcore reported by CPUID is 1.336v.
 
if your happy with the 4.5, and who wouldn't be..I would use manual voltage control and try dropping the voltage a bit at a time...no reason to let it go higher than needed...

My sons 2500 does 4.5 at 1.300..yours probably will also
 
I had my 2500K running stable @4.5ghz with manual voltage @1.25v. Ran Prime95 for 24 hours now problem. That's where I've had it for 3 months, until last week when I took it up to 4.6ghz @ 1.30 with intentions of seeing how far I can push it. So far stable at 4.6ghz.
 
pontiac4life said:
He said that he already tried 4.4Ghz at 1.31v and bombed so at 4.5Ghz and 1.33v is pretty close
Click to expand...

no, he said he used offset voltage..which unless your really familiar with can cause stability problems with higher overclocks...especially if its on auto

I tinkered momentarily with Offset voltage mode, applying a -0.025 to my 4.4ghz overclock, in an attempt to bring it back down to 1.31ish but prime95 bombed as soon as it started up. Seems that automatic voltage, or a + offset is the way to go?
Click to expand...


Manual voltage is the way to go
 
I'm back at this again. I'm taking offset voltage much slower. I'm not quite sure I understand the point.

With my voltage on Manual/Auto, I get 1.336v at 4.5ghz. Idle is 1.012v or so.

With offset at -0.015v, I get 1.360v at 4.5ghz. Idle is 0.976v.

If I bump the offset to the next possible value, -0.020v, I get crashes before I can even get to the Desktop. I assume the idle voltage goes too low. Not sure why auto voltage is giving me lower load voltages, but higher idle voltages. Seems like I can't have both a low idle and low load. I may just try a fixed voltage to see what I can do there. It will be more predictable at least.
 
Ohhh, the games have begun. Learning all kinds of new things here that probably aren't new to others. In any case, this is what I've learned from my offset voltage testing:

I started at a nice easy 4.2ghz overclock to get my head around things. First I started with "CPU Load-line Calibration" (LLC) set to "Ultra High" aka 75%. This gave me the following voltages:

Offset testing - 4.2ghz, LLC at 75%
auto - idle 1.008v, load 1.392v
-0.005 - idle 0.968v, load 1.352v
-0.010 - idle 0.960v, load 1.352v
-0.015 - idle 0.960v, load 1.344v
-0.020 - idle 0.952v, load 1.344v

Basically, the load vcore was much higher than required. As I increased the negative offset, my idle voltages started to get into dangerously low territory while my load voltages didn't decrease fast enough. This was not a workable option. So I went in and lowered the LLC. Lowering the LLC setting lowers the load vcore. The idle voltages stay the same. This is exactly what I needed:

Offset testing - 4.2ghz, LLC at 50%
-0.015 - idle 0.960v, load 1.320v

So now, I could drop my raise my offset a bit to -0.015 which brought the idle back up to a good range, and now the load voltages were down. So, I went to the next setting, LLC 25%:

Offset test - 4.2ghz, LLC at 25%
-0.015 - idle 0.960v, load 1.288v

Again, idle stays the same, as expected. But the load voltages are down even further. Excellent, I've figured it out! From my testing, and please correct me if I'm wrong, LLC controls how much voltage the CPU will get under load (controls vdroop). This can then be fine tuned with the offset setting. Now I can keep low voltages at idle with the appropriate voltages at load.

I'm still working with 4.5ghz to find the best ranges.
 
I apologize in advance if this is hijacking but, are offsets recommended for a mild OC?

I've have my 2500k for a few months now with intention on OC'ing. Looking for a modest 4-4.5ghz range. Current stock at 1.35v and OC virgin.
 
B!nd. said:
I apologize in advance if this is hijacking but, are offsets recommended for a mild OC?

I've have my 2500k for a few months now with intention on OC'ing. Looking for a modest 4-4.5ghz range. Current stock at 1.35v and OC virgin.
Click to expand...

Yes, you need to use offset voltage so that the vcore will drop based on load.

If you use manual voltage then you will be at your max voltage 100% of the time.

manual voltage is good for finding your desired stable OC and voltage (IE 4.7ghz @ 1.4v) once you have found your desired settings with manual voltage you can then switch it over to offset voltage and fine tune the settings there.

Offset voltage does get a little confusing with LLC enabled as the OP has found out already, so it does take some playing around with to find the "sweet spot".
 
leeleatherwood said:
Yes, you need to use offset voltage so that the vcore will drop based on load.

If you use manual voltage then you will be at your max voltage 100% of the time.

manual voltage is good for finding your desired stable OC and voltage (IE 4.7ghz @ 1.4v) once you have found your desired settings with manual voltage you can then switch it over to offset voltage and fine tune the settings there.

Offset voltage does get a little confusing with LLC enabled as the OP has found out already, so it does take some playing around with to find the "sweet spot".
Click to expand...

Thanks, that makes sense but unfortunately makes things more complicated. I'll have to look around to find some beginner tips.
 
This is a great question. I just got my new rig put together tonight and I am still tweaking.

10 minutes of Orthos and my temps are still at 52C - 54C - this H80 is pretty awesome, its not even on the highest setting.

Here's my cpuz validation - http://valid.canardpc.com/show_oc.php?id=2484801

So I gues I should ask, how high should I go? It feels like 5g's is withing the realm of possibility. I say that because it will POST at 5, but it BSOD's loading Windows. I have only pushed the volts as high as 1.3, though.
 
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