The chaps over at iXBTlabs.com take a further look at the Intel Core i5-660/661 Processors. Here's a bit:

Many users thought that the Core i5-600 would be like Core 2 Duo, just better -- a very fast processor for single and dual-threaded tasks. Unfortunately, we have to disappoint them: multi-threading is meat and drink for these CPUs, they need it as much as higher-end processors do. As soon as older non-optimized applications become involved, it turns out that the Core 2 Duo E8000 series remains unconquered. Even the new architecture and Turbo Boost doesn't help, because 4MB of 2.13 GHz cache is not the same as 6MB of 3+ GHz cache. Besides, Hyper-Threading is a disadvantage under these conditions. By the way, this is also the reason the main character of the review cannot compete with the Core i5-750 in the same situation: the latter has more cache, no HT, and it boosts clock rate aggressively when only two cores are used. In other words, Intel did the right things, having spent the entire last year persuading software developers to move to true multi-threading. And the company was even quite successful, but it was actually AMD who enjoyed the results most.

This is not Intel's engineers' fault, they have made a very good processor (compared to Intel's older products). The 10% boost in the total score comparing to the Core 2 Duo E8600 is very good. It's even better considering manufacturability, because the Clarkdale is much cheaper to make than the Wolfdale. As we could see, the E8600 only catches up with the Athlon II X4 630, while the Core i5-66x outperforms that fair quad-core processor easily. The price is not beneficial though. Such competition should have been avoided. Who is to blame? Those responsible for long-term decisions about rolling out solutions to the market. Users just relaxed, they got used to thinking that the Core 2 architecture was competitive enough. Nice numbers advertised for the new architecture did their part too. As a result, the company took its time, considering there would be enough time for everything: cooperation with software developers, implementation of the new platform, mastering of the new process technology. The rollout of the LGA1156 was delayed by three months due to commonplace pressure from motherboard makers which accumulated lots of LGA775 sockets and chipsets. The step-by-step implementation of the new platform resulted in three sockets existing simultaneously in the Intel's share of the market. Moreover, the company gave much praise to wonderful performance offered by the future hexa-core Gulftown ("Hmm, so the high-performance segment is going to be owned by LGA1366," users thought), to the benefits of the new architecture which was being developed and expected to go live late in 2010 ("Hmm, so they're going to change the socket again, meaning the current ones are equally unpromising"). However, in stores, users with two hundred bucks or less could only see the same old LGA775 processors. Obviously, no one knew what to choose.