Intel Core 2 Duo 'Conroe' E6400, E6600, E6700, X6800 Review

Without a doubt, Core 2 Duo or "Conroe" as it is code-named has been one of the most anticipated product launches in the hardware community for quite some time. Everybody has been waiting to see if Intel can claim back the performance crown and push under the rug the disappointment that was the NetBurst architecture. The string of Pentium 4/NetBurst products that Intel released had so many faults that I won't embarrass Intel by listing them. Put simply, NetBurst never reached the potential Intel believed it was capable of. However, financially it did very well as Intel is incredibly good at marketing, while AMD seems happy to sit by as the underdog expecting PC enthusiasts to do all its advertising for it.

On a number of occasions I've had the opportunity to play with Pentium M on desktop motherboards and it has been the closest experience yet to re-creating my Mendocino Celeron A overclocking days. So naturally, I have been looking to Conroe with anticipation.

Conroe is nothing like any previous Pentium 4 products. In fact, it's based on the mobile Core Duo design which is in itself based on Pentium M, which is based on Pentium 3 architecture. So Intel has actually done a bit of a U-turn.

Compared to Pentium 4, Core Duo (not to be confused with Core 2 Duo) offers low power consumption, low waste heat and high performance per clock. This is almost an exact opposite to the Pentium 4 which used so much power that the ATX specification had to be modified to add more 12V rails, and produced so much heat that they often throttled and made reaching 4GHz almost impossible. Not only this, but clock for clock performance wasn't stellar – hence the need for higher clock speeds in the first place. The resultant disparity between AMDs and Intel's clock speed was one of the primary reasons for AMD introducing PR ratings (eg. 5000+) so that consumers didn't feel like they were getting a raw deal.

Core 2 Duo is the next generation on from Core Duo. Although we have tested the desktop "Conroe" version of the Core 2 Duo processor here today, there will be a mobile version code-named "Merom". Although this will be architecturally identical, it will have better power saving technology for extended battery life.

AMD's biggest selling point has been its on die memory controller. This has had a lot of knock on effects (such as almost identical performance from motherboard to motherboard), but the main effect is a huge reduction in memory latency as communication is no longer passed through the north bridge. This, in combination with HyperTransport reduced the bottleneck of the front side bus. Memory performance affects system performance significantly, so Intel processors were suffering in this area a lot.

Intel's solution to this is several minor improvements to the Core architecture in order to reduce this memory latency and increase overall system performance. Most of these optimisations are quite minor, but put together add up to more than the sum of their parts. Quite frankly, how Intel has improved their architecture so much is largely irrelevant - performance figures tell us all we need to know.

Possibly the biggest improvement is an added pipeline. Where as Core Duo can complete three instructions per cycle, Core 2 Duo can now complete four which an obvious increase in processing power and efficiency.

To help reduce bottlenecks, the front side bus has been increased to 1,066MHz from the 800Mhz that all but a few of the processors used. This is at a base frequency of 266MHz, quad pumped.

If it wasn't completely obvious, the "Duo" portion of the name indicates that these are dual-core processors. Unlike previous Pentium D processors, these use a shared Level 2 cache (2MB or 4MB depending on the processor). This can be dynamically allocated depending on the task being run. For instance, if running an application that isn't multi-threaded (i.e. can't take advantage of a second core), then the primary core would get the full 4MB of Level 2 cache. Having more Level 2 cache means that fewer requests need to be made to the system memory – one of the biggest causes of latency.