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Disable cores for higher O.C.?

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a b à CPUs
a b K Overclocking
April 15, 2011 3:55:33 PM

I have a Phenom ii x4 965BE and i've hit a wall at 3.9ghz.
I was wondering would it be at all possible to reach a higher O.C. if i disabled 1 or 2 cores?

More about : disable cores higher

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a b K Overclocking
April 15, 2011 4:23:11 PM
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It makes logical sense that if your cpu has less cores it will run cooler and consume less power so I would assume that you would be able to achieve a higher overclock.

A quad core @ 3.9GHz should be just fine. I would rather run 4 cores at 3.9GHz that 3 cores at 4.2 - 4.3GHz.

Why not just check yourself? Disable 1 core and bump up the multiplier or bus speed and see what happens. I have been wondering about this too...
a b à CPUs
a b K Overclocking
April 15, 2011 4:31:10 PM

I could do that but i wanted to save the hastle.If someone knew the direct answer it would easiest.

Power/cooling isn't really an issue it's just the limiations of this processor.I don't see the point in going from 1.425v to 1.5v just to get it over the 4ghz hump/wall.
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a b K Overclocking
April 15, 2011 5:00:52 PM

Yea, I also don't feel like disabling a core on my i5 just to test.

Most of the time when a cpu hits an overclock wall it is just one of the cores that can't handle it. For example if core #2 is the weakest core and cannot go further than 3.9GHz and then you disable core #4 you will still be limited by core #2 and will be stuck at 3.9Ghz.

However, if core #4 is the weakest and you disable it then you should be able to go over 4.0GHz with core #1, #2 and #3.

This is all assuming that if you disable a core, core #4 is always the core that will be disabled.
a b à CPUs
a c 100 K Overclocking
April 15, 2011 5:33:05 PM

Yes it should increase your OC limit, but your performance would generally suffer as more cores tend to be better than fast cores... And as for how much it would increase, probably not a lot.
a b K Overclocking
April 16, 2011 4:18:10 AM

disabling cores just for the sake of overclocking is pointless.

rather stay at 4 cores than to go over the 4ghz barrier.

If your chip can't hit 4.0ghz with four cores, then just give up and stay at 3.9.

it's like a box of juice, you ran out of juice to suck, you can't just add water in and expect it to taste as good. It will be more full though, i can assure you that. (higher oc wise).
a c 172 à CPUs
a c 197 K Overclocking
April 16, 2011 1:31:40 PM

Sure. 4 cores at 3.9 GHz is 15.6 GHz. 3 cores at 4.2 GHz is only 12.6 GHz. :) 

You mean it doesn't work that way? :o 
a b K Overclocking
April 16, 2011 2:08:52 PM

Na, I'm sure it does :lol: 
a b à CPUs
a b K Overclocking
April 16, 2011 3:49:00 PM

Thanks for all the suggestions guys.
a b à CPUs
a b K Overclocking
April 16, 2011 3:49:46 PM

Best answer selected by purple stank.
April 16, 2011 8:28:52 PM

This is interesting. I'm running my Q6600 at 3.55GHz and have had it as high as 3.9GHz (all cores). I don't know if you were at all interested in gaming performance, or if you were just simply going for the highest clock on your CPU, but I'll do a simple Crysis cpu benchmark (low resolution and maxed physics settings) with my current settings, and with a higher o/c with 2 cores disabled and report back. I'm excited! :D 
a b à CPUs
a b K Overclocking
April 16, 2011 8:34:22 PM

I'm intrested in both gaming performance and a high O.C.
April 16, 2011 8:57:11 PM

Here we go.

I used the Crysis Benchmarking utility set on "benchmark_cpu" (the one with a lot of frags and rockets destroying buildings). I used settings that I felt would remove any GPU bottleneck so that differences in CPU speed would be more apparent.

Settings:
-DX10 32bit
-All settings at "medium" with particle and physics quality to "very high"
-1280x1024 resolution

Q6600 @ 3.55Ghz, all cores enabled
-Minimum FPS=51.76
-Maximum FPS=102.12
-Average=79.34

Q6600 @ 3.75Ghz, running dual-core (2 cores disabled in BIOS)
-Minimum FPS=31.97
-Maximum FPS=109
-Average=63.36

All values are an average of 3 benchmark runs.

I'm convinced that these numbers show that there is no way, with my setup, that I could get 2 cores to perform better than 4, even if I went for a 4.0Ghz clock (which I may try for the heck of it =P. It may be worth testing with disabled cores for a maximum overclock, but for raw performance, I'd keep everything enabled.

Here are my 4.0Ghz (2-cores) results:
-Minimum FPS=32.59
-Maximum FPS=112.76
-Average=65.7

Thats less than a 2 FPS (Avg.) gain over 2 cores at 3.75Ghz and still 14 FPS shy of my 4-core performance at 3.55Ghz.

I can't say my results weren't expected, but I love running tests and seeing the numbers. As an added note, I had to bump up my Vcore to 1.43V (from 1.32) to run the tests at 4Ghz. Extra voltage and heat might even make o/c testing a waste of time and potentially dangerous to your CPU. Keep a close eye on your temps if you decide to really push things (even if it is only on half of your cores).

June 4, 2011 4:06:00 AM

I know this thread is a couple months old but I thought that I would add some thoughts.

The conclusion you came to is generally correct for this scenario. Leaving your system @ 4 cores will give you optimal performance for the vast majority of programs/apps/games you use.

That being said, there are some benefits to disabling cores to achieve a higher overclock, but it is dependent on the software/game being used. Some (even recent) games were not coded with multi-core utilization in mind and are limited to using say 1 or 2 cores total of the 4 you have. Oblivion, for example, came out about 5 years ago and will only use at most 2 cores, but is a *very* processor intensive game, especially with all the additions and mods that have enriched it over the years. For a game like this, you *will* see a more dramatic improvement in performance by improving the clock speed on the processor, but the game will just ignore any cores past the 2 it's using. I personally have an AMD Phenom 2 B55 (quad core, unlocked 555BE) and use a 3.6GHZ 4-core profile for pretty much everything I do, but I set up an additional profile in my mobo's bios (it has 3 presets) to only have 2 cores active if I choose and clock them @ 4ghz. This does give Oblivion and other 'non-optimized-for-3+core' programs a significant boost, very noticeable in-game. On the other hand, games like GTA4 and the Crysis series run remarkably slower because they are optimized to take advantage of 3+cores.


Remember if you are planning on making a separate profile like this, be sure to test it for stability *THOROUGHLY*. Extensive testing is the only way to be comfortable with a setup like this. 12 hours of prime95, 12 hours memtestx86 (or 64),windows memory diagnostic extended test (at least 2 passes), LINX, OCCT, etc..

Don't fool yourself into thinking that just because you are able to boot into windows and things are running well that your work is done. Test, test, test. And then test a little more just to be safe =P. Catastrophic failure could result if you don't. Just my 2cents.

/M.Walfish
June 19, 2011 4:03:40 PM

although it would help u overclock but on longer run it wont make any sense !
cause most of the games today run on minimum of 2-3 cores and optimum on four cores so chances of performance drop increases so my personal advice u dont need to overclock on the cost of dissabling your 1or 2 cores
June 26, 2012 11:50:22 PM

So here's my question, I have a quad core that has core number 3 as the weak link. With an equal load it runs about 8-9 degrees hotter than the other three cores. I would like to disable it but keep core number 4 running. So far all the ways I have found to disable cores dont allow you to choose a specific core.
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