With its July price cuts Intel lists both the 2.4 GHz quad-core Q6600 CPU and 3.0 GHz dual-core E3850 CPU for $266 in 1,000 unit trays (PDF) while the 2.4 GHz dual-core E6600 CPU lists for $244. With the Q6600 effectively being two E6600 dies in the same CPU package but slower in clock-speed than the E3850 users face several questions: Do four versus two cores help at all, and if so is it better to help slower cores than two faster ones?
Jeff Attwood looks at both questions, using reviews from Tech Report and Xbit Labs he concludes that more cores help in only some situations:
The results seem encouraging, until you take a look at the applications that benefit from quad-core-- the ones that aren't purely synthetic benchmarks are rendering, encoding, or scientific applications . It's the same old story. Beyond encoding and rendering tasks which are naturally amenable to parallelization, the task manager CPU graphs tell the sad tale of software that simply isn't written to exploit more than two CPUs.
Furthermore the slower Q6600 cannot make up for the E3850’s speed with more cores;
It's mostly what I would expect-- only rendering and encoding tasks exploit parallelism enough to overcome the 25% speed deficit between the dual and quad core CPUs. Outside of that specific niche, performance will actually suffer for most general purpose software if you choose a slower quad-core over a faster dual-core.
ExtremeTech.com looks further at the question of two versus four cores, comparing the 3.0 GHz dual-core E3850 to a 3.0 GHz quad-core QX6850 CPU and finds that for gaming there is little current advantage to use a quad-core CPU.