IBM Roadrunner

Roadrunner is the name of a next-generation supercomputer at the Los Alamos National Laboratory in New Mexico. Currently the world's fastest supercomputer. The computer is designed for a performance level of 1.6 petaflops peak, which it reached in June 2008,[1] and to be the world's first TOP500 Linpack sustained 1.0 petaflops system. IBM built the computer for the US Department of Energy. It is a hybrid design with almost 7,000 AMD Opteron dual core processors and almost 13,000 IBM PowerXCell 8i CPUs in special designed TriBlades connected by Infiniband.
The Roadrunner uses the Red Hat Enterprise Linux operating system and managed with xCAT. The world's most powerful computer, Roadrunner covers approximately 12,000 square feet (1,100 square meters). It became operational in 2008.
The US Department of Energy plans to use the computer for simulating how nuclear materials age and whether the aging nuclear weapon arsenal of the United States is safe and reliable. Other uses for the supercomputer include the sciences, financial, automotive and aerospace industries.

TriBlade
Logically, a TriBlade consists of four Opteron cores, four PowerXCell 8i CPUs, 16 GB Opteron and 16 GB Cell RAM.
Physically, a TriBlade consists of one LS21 Opteron blade, an expansion blade, and two QS22 Cell blades. The LS21 has two dual-core Opterons with 16GB memory for the whole blade, that is 4GB for each CPU. Each QS22 has two PowerXCell 8i CPUs and 8GB memory, which makes 4GB for each CPU (like on the LS21). The expansion blade connects the two QS22 via four PCIe x8 links to the LS21, two links for each QS22. It also provides outside connectivity via an Infiniband 4x DDR adapter. This makes a total width of four slots for a single TriBlade. Three TriBlades fit into one BladeCenter H chassis.

Connected Unit (CU)
A connected unit is 60 BladeCenter H full of TriBlades, that is 180 TriBlades. All TriBlades are connected to a 288-port Voltaire ISR2012 Infiniband switch. Each CU also has access to the Panasas file system through twelve System x3655 machines.
CU system information:
360 dual-core Opterons with 2.88 TB RAM
720 PowerXCell cores with 2.88 TB RAM
12 System x3655 with dual 10GBit Ethernet each
288-port Voltaire ISR2012 switch with 192 Infiniband 4x DDR links (180 TriBlades and twelve I/O nodes)

Roadrunner cluster
The final cluster is made up of 18 connected unit, which are connected via eight additional (second-stage) ISR2012 switches. Each CU is connected through twelve uplinks each second-stage switch, that makes a total of 96 uplink connections.
Overall system information:
6.480 dual-core Opterons with 51.8 TB RAM (in 3.240 LS21 blades)
12.960 Cell cores with 51.8 TB RAM (in 6.480 QS22 blades)
216 System x3655 I/O nodes
26 288-port ISR2012 Infiniband 4x DDR switches
296 racks