| Intel Sandy Bridge Overclocking Guide |  |
| Articles - Featured Guides | |
| Written by Servando Silva | |
| Tuesday, 19 April 2011 | |
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Page 7 of 10
Overclocking Frequency vs. VoltageFor all you readers who decided to jump the first pages and go straight to the results, I must repeat that there's no interest on testing performance's difference between non overclocked and overclocked setups. That point has been addressed in all our CPU/Motherboard/RAM reviews we've done in the past, and it's up to you to decide whether you need to overclock or not, and how much is "enough" for you. Getting to the point, in this first section I'll be showing how CPU frequency increases against CPU vCore. All those charts are the result of several hours trying and testing different settings and the results reported were 100% stable (considering the stability's paradigm explained before).
As you can see, both Sandy Bridge processors have a vCore around 1.1 volts. This is the reason Sandy Bridge achieves pretty good temps at load conditions at factory settings. The first step was bumping CPU frequency to 4GHz. For this, I just increased CPU multiplier to 40x and added a few milli-volts to the vCore. Both processors were able to achieve 4GHz with 1.15v, which is a very outstanding result. Let's keep in mind that Lynnfield and Nehalem processors needed more voltage (around 1.3v or more) to achieve 4GHz. The only processors able to reach 4GHz almost at stock voltage were the Core i3 and Core i5 Clarkdale CPUs, but all of them worked with 2 cores/4 threads. With Sandy Bridge we're not going to break any record at 4GHz, so my next step was passing to 4.4GHz. I'd say this is the best frequency according to CPU temperature and power consumption. It required something around 1.25v to keep both processors rock stable. Up to this point, it seems both the Core i5 and the Core i7 require similar voltages to achieve the same frequencies. However, let's not forget that the i7 has 2MB of extra L3 cache and works with Hyper Threading technology. Finally, I set my highest stable point at 4.8GH. I needed almost 1.4v for the Core i7 and 1.4v for the Core i5 in order to achieve a stable platform here. With those voltages, the CPUs reached the limit and the temperatures raised a lot against stock settings. Just for fun, I tried getting 5GHz stable without any success. I would need a better motherboard and probably a better heatsink with more than 1.45v in order to achieve my dream, but I didn't want to risk any of my CPUs just for a test.
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Comments
Take care.
Not to get too far away from your core article regarding Sandy Bridge, but do you have any insight as to whether or not AMD will maintain OC potential in their new lineup?
You know that phrase: "Like the old days". I'm not saying I don't like this new way of overclocking. Actually, I like not to pass several hours to find such a nasty or complex configuration for my PC, and doing it the the old way. New OC tools and features help a lot when what you just need is to bump your PC speed and get back to work, but sometimes it was funny to test and read a lot for that.
Also, sub-zero overclocking is quite fun, but with Sandy Bridge they somehow killed it.
Regarding the new AMD processors, I still have no information about them, so I'm anxious to test one.
And certainly the advantages of having a MB/CPU combo that is "self-monitoring" power, thrust, pitch and yaw outweigh the "good old days". And yes, I mostly like automatic transmissions over three-on-the-tree these days as well.
You can say that again! I read somewhere that Sandy Bridge reach its peak performance at about 20C. If you cool it more than that it won't reach quite as high speeds.
I've heard some processors do worst when going below 10-20C degrees. Again, it's good because now many users will be able to play and overclock without going extreme, but it won't be as interesting for extreme users.
Max Core Temps under (Idle - P95 load)
GHz..... 3.8 ... 4.00 ...... 4.2 ........ 4.4 ........ 4.6 ....... 4.80
Core 1 (51) (31 - 52) (29 - 54) (29 - 56) (31 - 62) (29 - 69)
Core 2 (53) (30 - 54) (30 - 56) (30 - 60) (31 - 66) (28 - 75)
Core 3 (53) (23 - 55) (22 - 57) (22 - 60) (31 - 68) (28 - 79)
Core 4 (51) (29 - 52) (28 - 55) (29 - 57) )31 - 65) (28 - 72)
Hope that formats well
What I am thinking now is making a "gaming profile" w/ HT turned off since I can prolly drop 7 - 10C at 4.8 Ghz ..... will give it a # when kid gets back in school but wondering if anyone's tried yet on SB.