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The Problem with Overclocking

Posted on 21st Dec 2009 at 10:50 by Clive Webster with 20 comments

Clive Webster
For some completely unknown reason (alright, just one I can’t tell you yet), I’ve spent most of last week testing and overclocking CPUs. Because of the way the magazine deadlines work in the run-up to Christmas, deadlines are tight, but the urge to get the very last MHz from a CPU still bit me pretty hard.

One of the CPUs I was testing was a Core 2 Duo E7400 – we’d previously seen that the E7300 could overclock from 2.66GHz to 4.2GHz, and I was sure I could 4.3GHz out of it. In fact, I initially tried for 4.4GHz but just couldn’t get the second core stable under Prime. Nothing I tried could get that second core to play ball – the worker thread on Prime95 crashed out the moment I kicked in the smallfft test.

Normally we head off home at 6pm (we start at 10am, so it’s still an eight hour day) but here I was at ten to eight in the evening tapping numbers into my calculator, determined to get 4.3GHz out of the chip. I was played with the GTL for the second core, trying various combinations of PLL and vcore and generally trying everything I could to get that troublesome second core to work. Finally, after many restarts and failed attempts, I conceded that 4.3GHz wasn’t possible.

I quickly verified that 4.2GHz was fine, and, glancing at my watch to see it was now past 8pm, I tried to get the bloody CPU as close to 4.3GHz as possible. Why? Why did I do that? What difference was it going to make to any benchmark – let alone the review itself – if the CPU was clocked at 4.25GHz or 4.28GHz? What was I going to prove? I took me five or six further failed attempts to realise that actually the CPU wasn’t going to go any higher and I should settle for 4.25GHz.

The weird thing is, a few of years ago I’d have been thoroughly chuffed with a 52 per cent overclock for two hours of BIOS fiddling. The other night it just felt like a failure… This is just one of the many problems with overclocking, but my sleep-deprived, blood-shot left eye makes this particular issue the most annoying. Where do you draw the line between a worthwhile amount of performance gains for the time you've invested?

20 Comments

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proxess 21st December 2009, 12:18 Quote
You don't draw lines. If I were you, I'd be kicking it in again until I got that 4.4!
feathers 21st December 2009, 14:09 Quote
How much of our lives do we waste on trivial pursuits? Look back over your life and add up the hours spent overclocking your bits. I've been overclocking since the days of the 486 (or was it 386?). I used to chill my P4 northwoods below zero with peltier and water (happy days) and spent many hours decorating the inside of my PC case with lights and UV braid.

That's the reason I don't do case mods. There are some really talented case modders out there but I personally feel that life is too short to spend modding a case to perfection (unless of course the end result wins me fame and fortune).

And, going back to overclocking... I have had an awful few weeks since I ditched my 3.84ghz overclocked Q6600 system in favour of i7 860 on EVGA FTW P55 and GSkill 1600mhz ram. Only after I made the change did I read forum comments across the web that the 860 isn't really that great at overclocking past 4ghz. Most people don't even get to 4.2ghz. Once you get past 4ghz you need massive voltage increase. I am not sure at this point that I made the right choice going to P55 platform.

My original plan was X58/920 but I was lured by the lower power consumption of the 860 and also the fact that the EVGA FTW has mounting holes for my skt 775 waterblock as well.

My main concern is that 1156 will be neglected and all the best cpu releases will be for skt 1366.
skunkmunkey 21st December 2009, 15:38 Quote
Im in exactly the same boat as you with identical hardware... But then I tend to do a full system upgrade every 6-10 months so its not so bad
feathers 21st December 2009, 15:45 Quote
My i7 system was BSODing every day since purchase 3 weeks ago.. I tried everything, finally I patched to latest EVGA bios and it's much more stable now. I like this EVGA motherboard. Very old school. My previous board was a Gigabyte UD3P and whilst it was much better than the awful Asus max extreme, it used to crash on first boot on cold mornings. The EVGA is much more stable even at very low temps.
Xir 21st December 2009, 16:10 Quote
...10:00-18:00 Job in journalism and worrying about 2 overhours :D

Just the envy speaking here ;)
Omnituens 21st December 2009, 17:02 Quote
What annoys me about overclocking when hardware just wont play ball.. you know it SHOULD be hitting a certain speed with ease, but refuses to. I'm having trouble getting my i7 920 above 3.5GHz now... really wish I had gone for the Asus board instead, the gigabtye one has show some design flaws :/
bobwya 21st December 2009, 17:31 Quote
IMHO it's a bad idea to push an OC unless you are going for some kind of record. The most useful OC will be able to run 24/7 in the summer, etc. Generally you need to leave GHz gap, to leave headroom, as most hardware will gradually loss OC headroom as it wears out with the stress of OC (especially if over-volting components). I prefer to spend hours on building and designing a rig (watercooling, etc.) I don't have much interest in spending days trying to get the best OC - I'd rather spend an hour or two tops - leaving it to burn in of course.

Totally agree about the MB. It's vital to have a really well built board to be able to cope with the extra signalling speed and volts demanded by an OC.
feathers 21st December 2009, 18:44 Quote
I agree. I need my overclock to be stable 24/7 rather than extreme and running only for a short time before crashing or burning out. Sometimes I have one overclock for summer and another for winter. With my old Q6600 that wasn't necessary. It could run at 3.84ghz summer and winter but I already know that won't be possible with this i7 system. At 4ghz and with my extreme water-cooling system (triple rad cooled by outside air), the cores get as hot as my Q6600 did in summer at 3.84ghz.
wuyanxu 21st December 2009, 20:42 Quote
that overtime might be a problem with journalism, but i am pretty sure it isn't a problem in the eyes of an overclocker.

what defines an overclocker? the will to squeeze every last drop of performance by tweaking BIOS settings (or jumper pins in the old days)

sure the time spent might not be worth it in terms of performance, but think of the achievement you feel once you have found the absolute maximum of your chip?

i have yet to find my i7 860's max clock speed, and i am really looking forward to do so. it would be a joy to tweak the new architecture and experiment with the settings.

on the other hand, 24/7 overclock is more important, and with the wear level in mind, a slightly lower overclock should be used. for the e7400 i'd say 4Ghz.

@feathers. the LGA1156 platform won't be left behind. it will cover the high-end down to the bottom end, no reason to get scared :)
also, 4Ghz on 860 is very easy as long as you have a lucky chip. low VID of 1.12v helped to get my i7 860 to 4Ghz with only 1.3v, same as other i7 920 chips.
pimonserry 21st December 2009, 20:47 Quote
And to think, my E8500 will barely hit 4GHz without getting toasty :(
feathers 21st December 2009, 20:58 Quote
@wuyanxu

4ghz has indeed been easy on 860. It was only let down by unstable BIOS on EVGA. That has now been rectified with A39 bios update. I don't think I have a lucky chip but I should spend some time to see if I can reduce the volts a little now. VTT = 1.36. Vcore 1.35 in windows. From what I've read, my volts are quite common for 860. Fudzilla's review of the EVGA FTW used similar volts to get to 4ghz and they also had problems getting 4.2ghz without massive voltage raise.

:)
wuyanxu 22nd December 2009, 01:21 Quote
had a quick play around. got to 4.3Ghz with 1.36v Prime stable for 30min, open case at around 85c. don't know anything beyond that as i have yet to find out exact max Bclk for this i7. the i5 i had in it was able to do up to 205Mhz.

i wouldn't say that's a large voltage increase. however from 3.8Ghz to 4Ghz does need a large-ish voltage increase, from 1.23v jump to 1.3v to pass my extensive stress tests.

and that also comes back to problems with overclocking. the 1.23v wasn't tested extensively as i just tested 1.2v found to be stable enough, and jacked up a bit on voltages just to be safe. very quick 30min of work. but to get 4Ghz stable without blowing up the CPU when running LinX (Lin pack GUI) i had to spend more than 2 hours just tweaking it and then there's the electricity bill for stress testing it over 4 nights. does the 200Mhz increase matter? is it worth the effort? YES for both question as i was able to achieve my goal of 4Ghz. on 4th morning, when i saw the stress test was still going without errors, i was so pleased.
wuyanxu 22nd December 2009, 01:21 Quote
had a quick play around. got to 4.3Ghz with 1.36v Prime stable for 30min, open case at around 85c. don't know anything beyond that as i have yet to find out exact max Bclk for this i7. the i5 i had in it was able to do up to 205Mhz.

i wouldn't say that's a large voltage increase. however from 3.8Ghz to 4Ghz does need a large-ish voltage increase, from 1.23v jump to 1.3v to pass my extensive stress tests.

and that also comes back to problems with overclocking. the 1.23v wasn't tested extensively as i just tested 1.2v found to be stable enough, and jacked up a bit on voltages just to be safe. very quick 30min of work. but to get 4Ghz stable without blowing up the CPU when running LinX (Lin pack GUI) i had to spend more than 2 hours just tweaking it and then there's the electricity bill for stress testing it over 4 nights. does the 200Mhz increase matter? is it worth the effort? YES for both question as i was able to achieve my goal of 4Ghz. on 4th morning, when i saw the stress test was still going without errors, i was so pleased.
feathers 22nd December 2009, 14:51 Quote
You have a lucky CPU. I can't get mine OCCT stable even at 4.2ghz with 1.42v CPU and 1.4v VTT. My experience is more typical though. Some people can get it stable 4.2 with 1.4v. A few can get it stable with far less volts. It was BSODding at first but at 1.42v cpu and 1.4v VTT it just causes a fail message in OCCT after about 1 or 2 mins.
Madness_3d 22nd December 2009, 23:27 Quote
I found when i had a Phenom II 940 that it just didnt give me the satisfaction of overclock.
It was prime stable at 3.69ghz....
thats an annoying number...
but come rain or shine it would not be prime happy past that.
Which is why I sold it to my brother and bought a 965 C3 ^__^

I think nowadays the spot that everyone wants if 4.0Ghz, because its well beyond the range of anything stock speed and when you say 4.xxGhz people know its something special. anything 3.xx its just not quite as good. Which is what makes me ecstatic about my 4.02GHz Prime stable OC. (oh and it'll post up to 4.64GHz too ^__^ )

wuyanxu is further proof of this theory ^_^ and same on the cpu cooler, it really is a beast. but with the fan set to voltage not pwm its silent too
wuyanxu 23rd December 2009, 00:32 Quote
Quote:
Originally Posted by Madness_3d
I found when i had a Phenom II 940 that it just didnt give me the satisfaction of overclock.
It was prime stable at 3.69ghz....
thats an annoying number...
but come rain or shine it would not be prime happy past that.
Which is why I sold it to my brother and bought a 965 C3 ^__^

I think nowadays the spot that everyone wants if 4.0Ghz, because its well beyond the range of anything stock speed and when you say 4.xxGhz people know its something special. anything 3.xx its just not quite as good. Which is what makes me ecstatic about my 4.02GHz Prime stable OC. (oh and it'll post up to 4.64GHz too ^__^ )

wuyanxu is further proof of this theory ^_^ and same on the cpu cooler, it really is a beast. but with the fan set to voltage not pwm its silent too
agree, it's the number that gets us, not the actual performance or possible electric bill :D

very nice OC at 4.6Ghz.
tk421 23rd December 2009, 12:51 Quote
i love my e7400 ... and that's a fairly major statement from a decidedly biased AMD fan.

knowing i can get rock-solid stable 3.5 out of a 2.8ghz chip, under a $20 air cooler, on a budget p43 mobo with OEM ddr2 800 ... for as little as i spent to put this rig together, is amazing to me.

i like it so much, i dug up another e7400, and plan on building a htpc around it and some found / donated parts... i'm curious to see how it handles an old 650i board. probably won't be overclocking the movie box though.
|V| 4 L k i 3 R 24th December 2009, 22:08 Quote
People who modify their vehicles have the same 'problem', if you want to call it that. They set out to hit an arbitrary, but specific number, whether it be in the 1/4 mile drag time, horsepower, torque, or anything else that can be tweeked. These numbers don't REALLY mean anything of themselves, but people use them to compare two different machines. I think it is the competitive nature of humans that drives you. Even if it only is a competition against yourself to do better. I have gotten to a point on my pc where I said, "I don't really care what the number is because it does exactly what I want it to do." I haven't quite gotten there on the car yet (still needs to be a bit quicker), but that's another story.
I think you ought to look at the number you started out with and the number you finished with and ask yourself, "What did I set out to do in the beginning?" and I think you may find the answer to be "To push this processor to it's limit" and you have found it's limit (for the time being).
Elton 24th December 2009, 22:48 Quote
I'm happy with a decent OC, stability + performance is where it's at.

leading to my 600mhz increase in my E8400 when I full well know that I can hit 4ghz.
thehippoz 27th December 2009, 20:57 Quote
Quote:
Originally Posted by pimonserry
And to think, my E8500 will barely hit 4GHz without getting toasty :(

the e7400 has a smaller cache.. it's a oc beast on a budget =] perfect chip really- and from a gaming point of view it's not about the cache as it is the speed

thing is if you plan on any kind of longevity (2yrs+).. you need to keep it under thermal specs 74.1C - and I go a step further and keep it at or under the max voltage spec (according to intel 1.3625v).. I always looked at it like who would know better about the chips limits and electromigration than intel's own engineers

http://processorfinder.intel.com/details.aspx?sSpec=SLGQ8

your pretty much guaranteed a good life on the chip
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