most benchs say having more cache only improves by 3-5%, which you can over achieve by bumping up the hertz...
Incomplete:
You really should have stated "depending upon application"...
(Apps that repeatedly loop the same instruction set over & over can gain via larger L2 cache onboard CPU setups, & apps that are examples of this are ones that calculate various things like distributed computing apps (SETI@Home &/or Folding@Home are examples of such apps))...
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E.G.->
Performance increases seen by increasing L2 cache:
http://www.karbosguide.com/books/pcarchitecture/chapter11.htm
"Here is a concrete example:
In January 2002 Intel released a new version of their top processor, the Pentium 4 (with the codename, “Northwood”). The clock frequency had been increased by 10%, so one might expect a 10% improvement in performance. But because the integrated L2 cache was also doubled from 256 to 512 KB, the gain was found to be all of 30%."
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Specifications: Socket 939 Athlon 64 X2 3800+
http://www.hothardware.com/viewarticle.aspx?articleid=710&cid=1
• With 128 Kbytes of L1 cache and 512K or 1MB of L2 cache per core, the AMD Athlon 64 and Athlon 64 X2 processors are able to excel at performing matrix calculations on arrays.
• Programs that use intensive large matrix calculations will benefit from fitting the entire matrix in the L2 cache.
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A GOOD READ FROM AMD ON HOW TO GET THE MOST OUT OF THE L2 CACHE (bit long & technical, but makes total sense):
Processor Cache 102: Accelerating AMD64
http://developer.amd.com/articles.jsp?id=85&num=1
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* This may hold "truer" for INTEL rigs, because of the diff.'s in memory controller hub's architecture between AMD & INTEL, & typically I have heard said that AMD has a far more efficient setup than INTEL does (even today) & also IF the cache is shared between cores, or exclusive "per-core".
The last article from AMD goes into that LAST point quite extensively in fact...
APK
P.S.=> Gamer's only usually see a 3-5% gain in their gaming tests of this L2 cachesize "controversy", & there, you would be correct, from any tests I have seen online...
However, again, apps that fit the above criteria (to name just some that do gain by larger L2 caches) get more than that... apk