Conclusion
We wanted to know how far users should overclock a modern Core i7 system before the main disadvantage of overclocking—high power consumption and processor overheating—would outweigh the benefits of higher performance, by reducing the performance per watt results. What we found was not too surprising.
Hardcore Overclocking is Not Practical
The 4.0 GHz setting came out as pretty much useless for anyone who remotely cares about heat dissipation and especially power consumption. Efficiency, measured in performance per watt-hour as used in the PCMark Vantage benchmark, even decreased by 17%, while all other overclocks increased in power efficiency. The benchmark required 50% more total and also average power than the 2.66 GHz default speed. The 95% increase in peak power would still appear somewhat acceptable for enthusiasts, but the 36% increase when idle is not, as this is the minimum power the system will require at any time it is running.
Stay Reasonable for Best Results
In the case of the Core i7 920, the best setting was 3.66 GHz—at this level, the CPU delivered a massive performance boost when compared to the 2.66 GHz stock speed, while still not introducing excessive power consumption. We found that the 3.33 GHz setting makes even more sense for average users, as virtually any X58 platform for Core i7 allows the user to easily overclock the Core i7 920 from 2.66 to 3.33 GHz by increasing the system clock speed from 133 MHz to 166 MHz. You can even keep the Core i7 Turbo Mode, which accelerates an individual core by up to two multiplier increments at peak single thread load.
Related Stories :
- IDF: Core i7 Will Self Overclock
- ORIGIN PC Overclocks New Core i7 to 5.0 GHz
- Overclocking Core i7: Power Versus Performance
- Overclocking: Core i7 Vs. Phenom II
- Editor's Corner: Overclocking Core i7
- Deals May 20: Alienware X51 Core i7 mini Gaming PC $999
- Habey Launches Pro-6820 Fanless Core i7 Quad-Core System
- Next Intel NUC Will Carry Core i5 & i7 CPUs
- Deals April 11: HP ENVY Core i7 Laptop $599.99
- Deals March 13: Dell 15.6'' Core i7 Ultrabook $749.99
Interesting and insightful article. It might be interesting to do a similar analysis when the new D0 stepping is widely available. Thanks for including a variety of video encoding / editing benchmarks too.
No undervolting / underclocking? I'm sure you can greatly improve efficiency by doing something like a clock of around 2.4 ghz and a voltage of around 0.8 - 0.9 volts... Even in default you might be able to undervolt quite a bit...
i wish i had one
does this mean that AMD phenom2 is better than Intel when it comes to overclocking?
lol no, this one went from 2.66 to 4.0. In the other comparison with the Phenom II it went from 3.0 to 3.8.
What I find interesting is that both articles found the magic number to be 3.6 ghz.
3.6 - 3.8 seems to be the universal sweet-spot for any CPU that allows for the OC. I've OC'd my E8400 to 3.6 and get great results, anything higher might yield an FPS or 2 more, but at the possible expense of more power.
Ever since the stock P4 3.6ghz came out, the magic number has been 3.6, every new generation of CPUs since then, people have expected to get somewhat further, but IMO it's safe to say that without some radically new technology, the magic number will always be about 3.6.
I will stick with my q9650 overclocked to 4.0Ghz at 1.24v ntm the 8gb ram at 1066 mhz. lolz
Very good article. However , I do have a problem with the test being ran with an "engineering sample" chip. A lot of boxed I7's won't hit 3.66ghz without at least 1.35 volts. Good read though.
Nice article.
Thanks.
I always believe the sweet spot is half way of stock speed and max OC. In this case, 3.33GHz is the sweet spot while 3.66 means you got a good overclocker. Good read.
I second the need for a underclock/undervolt analysis. Also, how about seeing exactly how voltage affects the processor without changing the clock speed. Many people hit 3.8-4Ghz at lower voltages so a base comparison on how much voltage affects the power (theoretically squared relationship) would be helpful...
I agree from the results that the safest overclock is 3,33Ghz with turbo mode enabled, for the casual gamer.
Besides, you will not notice much difference in games running them at 3,33 or 3,66.
Also the life expectancy of overclocking the CPU @3,33, is longer than @3,66Ghz.
I wished sometimes 'underclocking' would be done at toms, to see how much power one can save when he's only writing documents, or browsing the web with such a powerful machine. I mean, unless you're a gamer, the computer stays most of the time in a passive mode (if not turned off).
About the 'magical number',this probably changes with the die. When a processor is created @ 45nm the best results might be 3,6Ghz; but these results should be different on larger or smaller dies (eg: 65nm, 95nm, or the upcoming 40nm, or 32nm). It also has to do with the materials used. Current 45nM processes by intel are done with high metal K gates and stuff, they allow greater overclocking to the standard silicon processors...
If everything goes like now, and processors on a smaller die (32 nm, 28nm,...) will be identical copies of current processors, we might see a trend that the smaller the die, the smaller the possible overclocking.
It all depends on how thick of a layer of insulation Intel uses between the transistors (in on-off switching by lack of words), and if they will invent or discover newer more efficient materials to develop processors or not.
I just ran some calculations on these power consumptions.
Assuming you keep your computer on 365/24/7, at peak power all the time:
-$104.49/year for a 2.66 Ghz
-$204.56/year for 4.0 Ghz
For a medium usage user: 365 days per year, 4 hours at peak, 20 hours at idle:
-$61.97/year for 2.66 Ghz
-$94.60/year for 4.0 Ghz
For a more modest user: 365 days per year, 2 hours at peak per day, 4 hours at idle:
-$17.62/year for 2.66 Ghz
-$29.15/year for 4.0 Ghz
This assumes 5.6 cents/kWh.
This is just to give everyone a more convenient way to track power. I know i don't have a feel for 100 W compared to 200 W.
Stock cooling??? I'm not believing that.
WRT undervolting, maybe we need new mobo features to allow custom "speedstep" features. Run the processor at max. OC speed when it needs it, then drop to stock speed or below when at idle or at low use.
these are good performance gains
. but its not something ground breaking. :|
Stock cooling??? I'm not believing that.WRT undervolting, maybe we need new mobo features to allow custom "speedstep" features. Run the processor at max. OC speed when it needs it, then drop to stock speed or below when at idle or at low use.
Thats what got me too, with the abundance of good and cheap air cooling solutions negating the effects of Intel's Overspeed protection shouldnt be hard even w/o a board with a BIOS option to that effect.
I know I would rather have a bios option for better underclocking, so it is more transparent. Like super speedstep, where it drops the multiplier even more
.
I can't see a reason for tom's to give underclocking numbers, until their are better native dynamic underclocking features on mobos. No one is going to manually under clock their computer when they go and change to writing documents... it needs to be automatic.
Assuming Thej's numbers are even close to accurate, then having that extra bit of under clocking won't save you anymore than $5-$10, because most core components will still be running taking juice.
This article was a convenient read, and even more convenient thanks to Thej =).