Late to the game, overclocked 2500k questions

[Theodore2017]

Hi everyone, first time posting here so I have a lot of curious questions regarding my overclock and overclocking in general.  I think I'll save some questions for separate threads so I can stay on topic here.

 

I have re-installed my 2500k and Asus Sabertooth motherboard.  These are my Overclock settings:

 

Multiplier:  48

Vcore:       1.425

DRAM:      1.5

VCCSA:     Auto

VCCIO:      Auto

CPU PLL:  Auto

PCH:          Auto
Load-line Calibration:      Ultra High

VRM Fixed Frequency:   400

Power Phase Control:     Fast

CPU Current Capability:  120

 

Prime95 v26.6 Blend Tests for 10 hours gets the following max core temps:

Core 0:  65

Core 1:  71

Core 2:  71

Core 3:  66

 

I'm quite happy with my overclock settings and it's stable when playing Rome 2 Total War and watching shows/movies/dramas, browsing the web, etc.  I've checked the LTT spreadsheet with all the OC stats but it doesn't cover everything I want to know.

I have learned A LOT overclocking in May still have some questions:

 

1)

Do people even bother to set specific voltages for the VCCSA, VCCIO, CPU PLL, PCH?  I left it on Auto through my entire overclocking/stability testing process.  I read a lot of forums/articles about those settings but I didn't feel comfortable messing with it.  I didn't know what volts to set to because I saw different advice from different forums/articles.

 

2)

Do most people actually tinker with the Load-line Calibration, VRM Fixed Frequency, Phase Control, and CPU Current Capability?  I did tinker with these and settled on the specs you see above.  But in many youtube videos and some articles, people seem to ONLY touch Vcore.  My PC may run stable at lower settings but I don't feel like doing more stress testing cuz it's summer.  And my CPU temps are very low when playing or general use.

 

3)

Does voltages alone kill the CPU?  Or is it just high temperatures?  Hypothetically, if you had really good cooling and kept the CPU below 65^oC then, it doesn't matter if you set Vcore to 1.7V?  Or regardless of the temperature, you should never set Vcore to 1.7V because the volts alone can damage it?

 

4)
Is Vcore the voltage that EACH core gets?  Or is it the whole CPU package?  I was experimenting with disabling 2 cores to try to push the 2 active cores faster.

Also, I'm wondering about disabling some cores(at stock speeds) when I do light tasks like watching movies/shows/dramas, so it uses less electricity and generate less heat(summer is hot ugh).

 

5)

What are people's overclocking "methodology"?  Is my 10 hours in Prime95 too short?  I started OC at 3.8Ghz and I increase 100Mhz each time.  So I didn't skip any Multiplier number.

Some speeds I deemed "minor milestones" I ran Prime95 for 30 mins on Small FFTs torture tests, then Blend Tests for 30 mins more.  Then, I increase the speed by 100Mhz.

Some speeds I deemed to be "major milestones" I ran Prime 95 for 6 hours on Small FFTs torture tests, then Blend Tests for 6 hours more.  Then increase the speed by 100Mhz.

At the higher speeds I rand Blend Tests for 10 hours.

 

Is this too thorough?  Is it not thorough enough?  Part of me feels like this is wasting a lot of electricity unnecessarily.  I'm certainly not going to run Prime95 for 24 to 48 hours, though I know there are people who do that.  I also know there are ppl who just run CPU stress test programs for like an hour and call it stable.

 

Part of me thinks most people just pick the max speed they want to overclock to and start tinkering with Vcore to get it to run at that max speed right away.  They would skip all the lower speeds.  But I've read/heard about the Silicon Lottery so you don't know your CPU's potential.  Even if temps remain low, your CPU may not be able to go faster than stock speeds.  So if you go straight for a 4.8Ghz OC right off the bat, you may end up wasting so much time(and a lot of BSODs) only to end up lowering your OC to just stock, or barely above stock speeds.  But if you spend time stability testing the lower speeds, and it turns out your CPU can go at like 5.0Ghz easy, then you'd feel like you wasted time/electricity.  What are people's thoughts on this?

 

I'm going to stop here cuz I'm not sure if this LOOOOOONG post will turn people off from even reading it LOL.

 

Thanks for any answers  I'm hoping to hear your opinions.

 

BACKROUND INFO FOR CONTEXT (if you're interested):

I bought the Intel Core i5-2500k, Asus Sabertooth P67 B3 Revision, Cooler Master V6GT back in December of 2012 along with all my PC components but I was total noob and didn't know enough about overclocking and didn't do it properly and it kept crashing/freezing during Shogun 2 Total War and had high temps and the fans were so loud.  I didn't know how to resolve it and life became busy with other things and I just left it.  Didn't play or use my PC(which was intended just for games).  In summer 2014, when I bought the Corsair H100i, I decided to buy a new CPU and motherboard because I thought I had damaged them during installation.  I was total noob, I even forgot to install the risers on the motherboard tray before installing the motherboard on top so it didn't even boot and I had to take it back to the store.  Long story.

 

A month ago my PC had problems that I narrowed it down to either my Core i5-3570k, or Asrock Z77 Extreme3, or Asus Strix GTX 970. I was almost certain it was not the graphics card.  I may ask about this in another thread.

 

[typographie]

 1/2: Modern processors (and by that I mean probably Sandy Bridge and onward) don't seem to require extensive tweaking of all those additional voltages and settings to achieve a good result. I've seen VCCSA and VCCIO mentioned in the context of memory overclocking, but rarely outside of that. LLC does get mentioned a bit, but I think it's more of an "as-needed" setting.

 

3: As I understand it, both heat AND voltage carry their own independent risks. A Vcore of 1.7 V is still not safe even if it (somehow) does not result in a dangerous load temperature. High temperature regardless of voltage is also unsafe. You should still try to maintain a safe voltage even if the resulting heat is still manageable. I'm not an engineer, and I can't say for certain that I fully understand the mechanisms at play here, but at the very least this advice errs on the side of caution if it errs at all.

 

4: I'm unsure about the voltage portion of the question. Shifting cores that aren't in use to a low-power state in order to boost the frequency of the remaining cores is already what Intel Turboboost does. I wouldn't actually disable cores in the BIOS for this reason, though.

 

5: This sounds like a bit of a cop-out to what could be a really in-depth answer, but it's entirely up to you how certain you need to be of your stability. If all you do is game, particularly alone, the stakes of getting a random crash aren't very high. You'll reboot, reload your save or rejoin a different server, and all you've probably lost is a few minutes of time. If you use your PC to do a lot of important work, you will need to validate your overclock until you feel very confident in it.

[Jumper118]

You ask all the right questions clearly dome a lot of research and put lots of time and effort in. 

 

1) most people don't because they cba but yes, I would set sa and io, would only set the pll if I was going for absolute max speed. Pch voltage is only required on Ivybridge chips when you need over 105 bclk to stop it cold bugging under Ln2. 

 

2) same as above, most people cba but I would. LLC is tricky though because software doesn't really measure voltage accurately in most cases. So unless you have voltage check points on the motherboard you cant tell what it is doing. As for phase speed and response time, they will use more power and run warmer the higher and faster they are set, so I wouldn't set them at full speed just so the motherboard vrm isn't as stressed. 

 

3) yes voltage alone can kill a cpu. Lots of people ran sandy at 1.5v+ under water with load temps of 40-50c and those chips tended to degrade within a 12-24months quite badly. 

 

4) the voltage will be the same on all cores. But the cpu will draw less current from the VRM so with 2 cores active it will use about 40% less power than 4 cores active, but I wouldn't worry about it as the gpu uses more power than a cpu anyway. 

 

5) yes you wasted quite at lot of time. I would have started at 4ghz and gone upto 4.4 then 4.6 then 4.7,4.8 etc. You have to look at the average and worse case for this type of cpu and think of a good place to start. 

 

It would also just run a quick 10-15mins at each stage and then start running longer tests once it reaches its limit. 

 

I would set a max safe voltage like 1.4v and just see how fast the cpu goes. I would never set say 5ghz and see how much voltage it needs to boot and work because like you say if you have a bad cpu you end up with 1.5v and then have to lower it anyway. 

[Theodore2017]

Thanks @typographie and @Jumper118  I really appreciate the replies!! :)  It gives me some reassurance of my overclocking.

 

1) 2)  I had a feeling the VCCSA and VCCIO was probably only necessary for RAM overclocking but I didn't see it mentioned much elsewhere.  I have no intention of overclocking the base clock so I'm glad I didn't touch them.  I do notice a major difference in LLC at Extreme vs Ultra High.  At extreme the Vcore spikes I see in HWMonitor are huge!  But on ultra high it's moderate.  It makes me think LLC of Low/Med/High probably have close to no impact.  Yea I have the settings at one notch

below max lol.  I installed an assistant fan on the Sabertooth motherboard, running at 60%.  It's pretty quiet and my temps are pretty cool.

 

3)  I suspected that to be the case so this is why I didn't push it further even though my temps are low.  Wow 12 to 24 months!  I won't push beyond 1.425V.

 

4)  I was only able to push 2 cores to 4.9Ghz with the other 2 disabled and I had set Vcore to 1.475V already.  The temps were under control.  But question 3) is why I pulled back.  I noticed when I am browsing, watching shows/dramas, there is a significant difference in Watts used when there is 2 cores disabled in BIOS.  I used stock/default speed/settings with 2 cores disabled when watching shows online, etc.  But gaming I will set 4 active cores at 4.8Ghz.

 

I'm aware the graphics card use more watts than the CPU but even while idle?  In GPU Tweak, it shows my GTX 970 max clock of 135Mhz and the fan is never on when watching tv shows.  So I think the graphics card is actually basically idling.  Or do you mean the GPU draws more power on idle anyways?

 

5)  I DEFINITELY will be spending less time overclocking at the lower speeds in future LOL.  I guess part of me was really curious to see the incremental temp increase.  I'll be doing something similar to what you said @Jumper118

 

Yea my rationale is basically what you said @typographie.  I just game on my desktop so I don't feel the need to run 24 hour tests.

 

THANKS again guys!!

[Delicieuxz]

That's a high voltage and LLC setting, but your temperatures seem good. I don't know if your current OC is good for longevity, though.

 

For my Sandy Bridge OCs, I've liked using a positive voltage offset with modest LLC (25% or 50% on my current 2600K system), while keeping voltage under 1.41v at its peaks. You can still reach your OC using a voltage offset, but with an offset it will only be running at 1.4v+ under full load, and will be more like 1.0v when idle, saving electricity, and CPU lifespan.

 

Regarding testing OCs incrementally, or immediately jumping to your target... If you know what performance you're wanting, and know the ins and outs of overclocking your CPU, then there's not really any reason to do a bunch of small incremental OCs before trying the target that you want to reach. You'll discover what the CPU needs to run at the target, or that it can't run at the target just by trying the target with average parameters, and then adjusting the parameters as needed.

[typographie]

16 hours ago, Theodore2017 said:

I'm aware the graphics card use more watts than the CPU but even while idle?  In GPU Tweak, it shows my GTX 970 max clock of 135Mhz and the fan is never on when watching tv shows.  So I think the graphics card is actually basically idling.  Or do you mean the GPU draws more power on idle anyways?

I think he was just contextualizing how much power a CPU actually draws, even under load, and that it's still less than most mid to high-end GPUs. So if you're concerned about using less electricity, a huge portion of that coming from your GPU.

 

At load, a high-end GPU blows away even an overclocked CPU in power draw. It's probably more than half of your system's total draw. At idle, I suspect a high-end GPU still draws a lot more than an idle CPU as well, but it's worth considering that a CPU doesn't get to be idle as often or for as long as a GPU when not playing a game. So in practice it may be closer.

[Theodore2017]

@Delicieuxz  oh THANKS for your input!!  Yea I heard about the offset method of overclocking but I'm anxious about it and aren't too familiar with it.  I may try that method for oc'ing future CPUs but I just went with the method I knew more about.  Also, I consider this time to be my first real "proper" overclock.  I wanted to play it a bit safe.  I'll learn more about the offset method in future.

 

Yea I should probably lower the LLC a bit more but I'm not worried about longevity since I'm planning to upgrade CPU, motherboard, RAM within a year so I can play games as close to max as possible   Depends if stores have a nice deal, maybe in December.  I just don't feel like stability testing anymore.   Oh and I run it at stock speeds with 2 cores disabled in BIOS for watching movies/shows so it's not running my OC for very many hours per week.  My desktop is just for games/moves/shows. I do everything else on my laptop.

Yea I am feeling more confident and less anxious about overclocking now after this experience so in future, I'll be starting at more average speeds/settings and see how it goes.

[Theodore2017]

@typographie  Yea he was probably talking about in the grand scheme of things, playing games for a couple hours pushes the GPU to draw more power than compared to my CPU, regardless if 2 cores are disabled or not for many, many hours.

 

Oh I know.  My 2500k at full load OC draws 105 watts max.  I think my GTX 970 draws at least 200W.  At idle it's probably pretty close in reality,   Thanks for your input man   I feel I got a better understanding for overclocking.

[chexor]

I'm using 2500k on p67 borad, and i found out that voltages for the VCCSA, VCCIO, CPU PLL, PCH make difference for me. I was crashing at 4.6Ghz whenever i went into windows, 1.35v. Then i did some research and set voltages like default values for DRAM etc, and it was stable after that. I'm stack with 212evo, so i cant go any higher then 4.6Ghz temp limit..

[Theodore2017]

@chexor  Oh, I did set the DRAM to 1.5V but the others I left on auto.  You're Vcore is 1.35V? That's less than my 1.425V.  So maybe if I set the CPU PLL and PCH, etc maybe I could lower my Vcore a bit.  How did you test the stability of that setup?  and how long?  What temps are getting with those settings when you run CPU stress test?  I'm just curious.  I'm probably not going to run CPU stress test again.  Cuz then I gotta run a 5 hour system test where I run Prime95 AND FurMark simultaneously to be assured my PC is stable  LOL.

Thanks for your input!

[chexor]

55 minutes ago, Theodore2017 said:

@chexor  Oh, I did set the DRAM to 1.5V but the others I left on auto.  You're Vcore is 1.35V? That's less than my 1.425V.  So maybe if I set the CPU PLL and PCH, etc maybe I could lower my Vcore a bit.  How did you test the stability of that setup?  and how long?  What temps are getting with those settings when you run CPU stress test?  I'm just curious.  I'm probably not going to run CPU stress test again.  Cuz then I gotta run a 5 hour system test where I run Prime95 AND FurMark simultaneously to be assured my PC is stable  LOL.

Thanks for your input!

Ye, i am on 1.35v right now, cant go any higher because temps are going above 80c. For DRAM you must set your default voltage, that depends on your memory (for me that's 1.6v). PCH voltage is on auto, when ever i try to put any value it is unstable i have no idea why.. Maybe because p67 chipset (pch is chipset voltage i think), and for CPU PLL it is 1.9v (again some valuse may vary, but in bios in right corner you should see what voltage is safe to write and if you go higher it will be written in RED text).

 

About stresstesting PC. Why are you even stressing your pc so hard  do few round with cinabench, prime95 for 1h and play some game that is cpu dependent and you will be good to go if that is stable, in 99% of cases if in 1h of prime you have no crash, you will be fine..

 

1.425v for 4.8 Ghz is not bad.. I have not heard of someone got 4.7Ghz on 1.4v or under that. It would be ideally if somehow you can get 5Ghz on 1.45v or anything lower then that.

If you are already bumping up voltage just take everything from that overclock what you can, because at the end, with voltage you are getting shorter cpu life > higher temps 

[Theodore2017]

@chexor Hey sorry for the really late reply!  Yea my DRAM default is 1.5V.  I checked it before.   Wow ur temps is 80C!  That's pretty hot.  I've heard a lot of good things about the 212 Evo so I'm surprised!  I hope that's when you do cpu stress test and not for when you're gaming and stuff.  Cuz my temps are really cool when I play games.  It's like around 58C.   It's so cool that I even unplugged my front intake  200mm fan and my rear exhaust 120mm fan. and my CPU fans of my Corsair H100i is set to 500RPM.  So I'm not worried about temps and I'm actually really happy with how quiet my desktop is running now.  I never took the time to tinker SO MUCH with my PC so I always had so many fans going.

 

If I try to push more Ghz it does become a little unstable even though my temps are cool.  I've think I've reached the limit of it.  It BSOD at 1.395V so I'm relatively content with 1.425V.  I could live on the edge and just lower the Vcore to 1.415V and NOT stability test AT ALL   hahhaha  Maybe oneday when I'm feeling lucky!  LOL  But in general I set that 10hour Prime95 "rule" cuz I like to be really sure it's stable.  During the whole process, I did get errors in Prime95 at around the 3 or 9 hour mark.  So to me, it's still not stable enough.

 

Thanks for the info about not really hearing anyone else getting 4.7Ghz under 1.4V.  My CPU definitely can't get to 5Ghz. haha unless I push to like over 1.475V lol. Not trying that.

 

Oh yea the BIOS text changes color from black to yellow, to pink to red when you increase the voltage.  LOL First time I saw that it made me a bit anxious.

 

My goal for this CPU is for it to work until I upgrade sometime between December and next May.  I'm content with it's performance.

Thanks for commenting!!   I enjoy hearing about other ppl's experience with the 2500k and overclocking in general.  So I can get a better feel for overclocking.