New Intel Microprocessors for Desktops

7/15 - Intel allowed those who've been benching the company's new Core 2 Duo and Core 2 Extreme microprocessors to publish their results Thursday at 12:00 A.M. in the morning. The outcome was a flurry of benchmarks on Friday.

Conroe is the codename of the processor. The brand names are Core 2 Duo and Core 2 Extreme. Core 2 Duo, by the way, is also the brand name for the mobile version of the Core 2 processor, which is not due out until August. Both desktop and mobile Core 2 processors are part of Intel's Core microarchitecture, which also includes the Xeon 5100 series, which went by the codename of Woodcrest.

The benchmark data that has been recently released is for the desktop Core 2 processor.

Desktop Core 2 is to come in different flavors: X6800, E6700, E6600, E6400, and E6300. The X6800 is the Core 2 Extreme. The E series is Core 2 Duo.

The sweet spot for many may be the E6600. This chip allows one to experience all that Core 2 has to offer, for about $300. The E6600 comes with a full 4MB of L2 cache, unlike the E6300 and E6400 parts, which only come with 2MB of cache.

As for the X6800, there's never been anything sweet about $999. The Core 2 Extreme runs a little faster, but more importantly, it is the only Core 2 chip to ship with with a completely unlocked multiplier. This can be of value to overclockers, if they want to run their CPU above stock speeds, while keeping other parts running at standard speeds. For some overclockers, an unlocked multi might be worth the price.

This was the first time most reviewers were able to write about the overclocking potential of Core 2. The Core 2 Extreme appears to be ideal for overclocking, "even though top-line processors are normally notorious for not being the best overclockers".

Unlike the Core 2 Extreme, ordinary Core 2 Duos shall be hard-locked. These chips can still be overclocked. In particular, the E6600 part looks like it provides overclockers with "champagne performance on a smaller budget".

With CPUs, size matters, but in reverse. The new CPU is smaller than previous generation chips. Part of this is manufacturing process. Intel uses 65nm process technology, while AMD still uses 90nm.

But not all of the small size is the result of process technology. The Pentium D 900 series also uses 65nm process technology, and yet Core 2 chips are smaller because they use fewer transistors. Maybe part of it has to do with the absence of hyper-threading in the new chips.

The Pentium D 800 series has 2MB of non-shared cache. The Pentium D 900 4MB non-shared. Core 2 has either 4MB or 2MB of L2 cache, depending on the part. Unlike the Pentium D, however, the cache is shared between the two cores of Core 2. Much of the performance of the new chips resides in the shared cache.

One reviewer in particular tested to see what type of difference 2MB of cache makes from 4MB of cache. He found that the difference was sometimes significant (by as much as 10%). Also, in the future, "as applications grow larger in their working data sets then the advantage of a larger cache will only become more visible".

One of the problems that Intel had with its previous generation chips was with memory latency, or the time it takes the chips to access memory. AMD integrates its memory controller on-die, so it doesn't have this problem. Preliminary benchmarks of Core 2 processors showed improvement with Intel's memory latency. However, Intel appears to have improved Core 2 even more.

Benchmarks now indicate that Core 2 beats the competition on some memory latency tests. Intel's Core 2 processors potentially "now offer even quicker memory access than AMD's Athlon 64 X2, without resorting to an on-die memory controller".

The reviewer also tested to see how much of a difference increasing the FSB (front-side bus) from 1066MHz to 1333MHz makes with the new chips. The FSB of Core 2 currently runs at 1066MHz, but Intel is supposed to release a 1333MHz part by the end of the year. Also, new high end Apple desktops may use the server version of Intel's Core microarchitecture, which runs at 1333MHz. This "may be the first time that an Apple system will be faster out of the box than an equivalently configured, non-overclocked PC".

A 1333MHz FSB doesn't make as much of a difference as the bump from 2MB to 4MB in L2 cache, but it is still significant.

One of Intel's upcoming processors, due out in the first quarter of next year, is a quad-core Core 2, aka Kentsfield. While a 1333MHz FSB benefits Core 2, the "benefit will increase even more as the first quad core desktop CPUs are introduced".

One topic currently being debated, since the release of the benchmarks, is whose processors have the best performance per watt (ppw). AMD has new Energy Efficient (EE) and EE Small Form Factor (SFF) processors that use less energy than Core 2 processors. However, the Core 2 processors also perform better. So who has the best performance per watt? Power "numbers heavily favor Intel".

In fact, in at least some tests, it seems Core 2 Extreme has even better ppw than Core 2 Duo: "in a complete turn around from what we've seen in the past, the highest end Core 2 processor is actually the most efficient (performance per Watt) processor in the lineup".

What we have in Core 2 is an entirely new class of CPU. "Intel's Core 2 Extreme X6800 didn't lose a single benchmark in our comparison; not a single one".

On the one hand, it should come as no surprise that the Core 2 Extreme outperforms the competition. It's clocked faster. However, what is more suprising is that a slower-clocked Core 2 Duo should outperform a higher clocked competitor's chip.

The CPU that is two steps down from the Core 2 Extreme (E6600) bettered the competition's "flagship in the vast majority of benchmarks".

Occassionally, even the slowest Core 2 offering performed as well as the previous best CPU in the world. "This is Intel's new $183 part offering performance equal to that of AMD's $1,000 flagship".

About the only bright spot in all of this for the competition is that the new chips make Intel's old chips look even worse. "The old Intel lineup of Pentium D processors is truly an embarrassment".

Core 2 processors should start becoming available around July 27, "the most impressive piece of silicon the world has ever seen".

Source: Anand Lal Shimpi

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