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.
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!
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.
-All settings at "medium" with particle and physics quality to "very high"
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:
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).
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.
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
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.