Starfire or E10K). In September 2004, Sun made available systems with UltraSPARC IV which was the first multi-core SPARC processor. It was followed by UltraSPARC IV+ in September 2005 and its revisions with higher clock speeds in 2007. These CPUs were used in the most powerful, enterprise class high-end CC-NUMA servers developed by Sun, such as the Sun Fire E15K and the Sun Fire E25K. In November 2005, Sun launched the UltraSPARC T1, notable for its ability to concurrently run 32 threads of execution on 8 processor cores. Its intent was to drive more efficient use of CPU resources, which is of particular importance in data centers, where there is an increasing need to reduce power and air conditioning demands, much of which comes from the heat generated by CPUs. The T1 was followed in 2007 by the UltraSPARC T2, which extended the number of threads per core from 4 to 8. Sun has open sourced the design specifications of both the T1 and T2 processors via the OpenSPARC project. In 2006, Sun ventured into the blade server (high density rack-mounted systems) market with the Sun Blade (distinct from the Sun Blade workstation). In April 2007, Sun released the SPARC Enterprise server products, jointly designed by Sun and Fujitsu and based on Fujitsu SPARC64 VI and later processors. The M-class SPARC Enterprise systems include high-end reliability and availability features. Later T-series servers have also been badged SPARC Enterprise rather than Sun Fire. In April 2008, Sun released servers with UltraSPARC T2 Plus, which is an SMP capable version of UltraSPARC T2, available in 2 or 4 processor configurations. It was the first CoolThreads CPU with multi-processor capability and it made possible to build standard rack-mounted servers that could simultaneously process up to massive 256 CPU threads in hardware (Sun SPARC Enterprise T5440), which is considered a record in the industry. Since 2010, all further development of Sun machines based on SPARC architecture (including new SPARC T-Series servers, SPARC T3 and T4 chips) is done as a part of Oracle Corporation hardware division. x86-based systems In the late 1980s, Sun also marketed an Intel 80386-based machine, the Sun386i; this was designed to be a hybrid system, running SunOS but at the same time supporting DOS applications. This only remained on the market for a brief time. A follow-up "486i" upgrade was announced but only a few prototype units were ever manufactured.