When assessing the Pentium D, it is important to note that it is essentially two CPUs in the same package and that it will face the same bus contention issues as a pair of Xeons prior to the Dual Independent Bus architecture introduced with the Dual-Core Dempsey Xeons. To use a crude analogy one could say that instead of using a single cable between CPU and north bridge, one must use a Y-splitter. Leaving aside advanced issues such as cache coherency, each core can only use half of the 800 MT/s FSB bandwidth when under heavy load. The competing Athlon 64 X2, although running at lower clock rates and lacking Hyper-threading, had some significant advantages over the Pentium D, such as an integrated memory controller, a high-speed HyperTransport bus, a shorter pipeline (12 stages compared to the Pentium D's 31), and better floating point performance, more than offsetting the difference in raw clock speed. Also, while the Athlon 64 X2 inherited mature multi-core control logic from the multi-core Opteron, the Pentium D was seemingly rushed to production and essentially consisted of two CPUs in the same package. Indeed, shortly after the launch of the mainstream Pentium D branded processors (26 May 2005) and the Athlon 64 X2 (31 May 2005), a consensus arose that AMD's implementation of multi-core was superior to that of the Pentium D. As a result of this and other factors, AMD surpassed Intel in CPU sales at US retail stores for a period of time, although Intel retained overall market leadership because of its exclusive relationships with direct sellers such as Dell. In 2007, Intel released a new line of desktop processors under the brand Pentium Dual Core, using the Core microarchitecture (which was based upon the Pentium M architecture, which was itself based upon the Pentium III). The newer Pentium Dual-Core processors give off considerably less heat (65 watt max) than the Pentium D (95 or 130 watt max). They also run at lower clock rates, only have up to 2 MB L2 Cache memory while the Pentium D has up to 2×2 MB, and they lack Hyper-threading. The Pentium Dual-Core has a wider execution unit (four issues wide compared to the Pentium D's three) and its 14 stages-long pipeline is less than half the length of the Pentium D's, allowing it to outperform the Pentium D in most applications despite having lower clock speeds and less L2 cache memory.