The Xbox 360 video game console features a port on the top when vertical (left side when horizontal) to which a custom-housed hard disk drive unit can be attached in sizes of either 20, 60, 120, 250, 320, 500 GB; the user can use the format option from system settings to initialize the new HDD. Inside, the Xbox 360 uses the triple-core IBM designed Xenon as its CPU, with each core capable of simultaneously processing two threads, and can therefore operate on up to six threads at once. Graphics processing is handled by the ATI Xenos, which has 10 MB of eDRAM. Its main memory pool is 512 MB in size. All games are required to support at least Dolby Digital 5.1 surround sound, and all versions of the console include a wired Ethernet network adapter.

Central processing unit (CPU)

Xbox 360 took a different approach to hardware compared to its predecessor. The XCPU, named Waternoose (later Loki), is a custom triple-core 64-bit PowerPC-based design by IBM. The CPU emphasized high floating point performance through multiple FPU and SIMD vector processors in each core. The SIMD vector processor (VMX128) was modified for the Xbox to include a dot-product instruction. The dot-product instruction took far less latency than discrete instructions. The VMX128 was also modified by the addition of Direct3D (D3D) compressed data format. This led to an approximate 50 percent savings in required band-width and memory footprint making the CPU having a theoretical peak performance of 115.2 GFLOPS, being capable of 9.6 billion dot products per second. Each core of the CPU was capable of simultaneous multithreading and was clocked at 3.2 GHz. However, to reduce CPU die size, complexity, cost, and power demands, the processor used in-order execution in contrast to the Intel Coppermine 128-based Pentium III used in the original Xbox, which used more complex out-of-order execution. The original chip used a 90 nm process, although a newer 65 nm process SOI revision was implemented on later models, which was in-turn superseded by a 45 nm, then 32 nm combined CPU and GPU chip. A 21.6 GB/s front side bus, aggregated 10.8 GB/s upstream and downstream, connected Xenon with the graphics processor/northbridge. Xenon was equipped with an 8th way set associative 1 MB Level 2 cache on-die running at half CPU clock speed. This cache was shared amongst the three CPU cores. Each core had separate L1 caches, each containing a two-way set associative 32-Kbyte L1 instruction cache and a four-way set associative 32-Kbyte L1 data cache. The write-through data cache did not allocate cache lines on writes. The CPU also contained ROM storing Microsoft private encrypted keys, used to decrypt game data. The heat sink implemented to cool the Xenon CPU was composed of aluminum fins with a copper base, and a heat pipe. Newer revisions, which had a smaller core, do not feature the heat pipe or copper base. The heat sink was cooled by two 70 mm fans at the rear of the console on original-style consoles, while a single fan mounted on the side of the consoles was used in Xbox 360 S consoles. There were several types of fans used in Xbox 360s, which were produced by Nidec, Sunon, and Delta Electronics.

CPU data streaming During read streaming into the CPU, a custom prefetch instruction, extended data cache block touch (xDCBT) prefetches data directly to the L1 data cache of the intended core, which skips putting the data in the L2 cache to avoid thrashing the L2 cache. Writes streaming from each core skip the L1 cache, due to its no-write allocation (avoids thrashing of high-bandwidth, transient, write-only data streams on the L1 cache), and goes directly to the L2 cache. The system allows for the GPU to directly read data produced by the CPU without going to main memory. In this specific case of data streaming, called Xbox procedural synthesis (XPS), the CPU is effectively a data decompressor, generating geometry on-the-fly for consumption by the GPU 3D core.

Graphics processing unit (GPU)

While the first Xbox's graphics processing unit was produced by Nvidia, the Xbox 360 had a chip designed by ATI called Xenos (later Gunga). The chip was developed under the name "C1" and "R500" was often used to refer to it. The GPU package contains two separate silicon dies, each built on a 90 nm process with a clock speed of 500 MHz; the GPU proper, manufactured by TSMC and a 10 MB eDRAM daughter-die, manufactured by NEC. Thanks to the daughter die, the Xenos can do 4× MSAA, z-buffering, and alpha blending with no appreciable performance penalty on the GPU. The GPU also houses additional capabilities typically separated into a motherboard chipset in PC systems, effectively replacing the northbridge chip. It has a theoretical peak of 240 GFLOPS. Early models of the GPU had reliability issues. This was fixed around mid 2008.

Memory and system bandwidth

The console features 512 MB of GDDR3 RAM clocked at 700 MHz with an effective transmission rate of 1.4 GHz on a 128-bit bus. The memory is shared by the CPU and the GPU via the unified memory architecture. This memory is produced by either Samsung or Qimonda.

According to Mark Rein of Epic Games, Microsoft had originally planned on using only 256 MB of RAM, but the decision to increase it was based on Epic's upcoming Gears of War title. Epic had been arguing for Microsoft to increase the memory for some time, and Tim Sweeney had sent Microsoft screenshots of what Gears would look like at 256 MB, and then at their proposed 512 MB. Mark Rein further claimed that Epic Games was the first studio to be told of the new 512 MB memory specification in a phone call with the chief financial officer of Microsoft Game Studios, with the CFO claiming the change would cost a billion dollars, Rein replied that the new specification was better for gamers.

The Xbox 360 has an extensive amount of bandwidth in comparison to its competition; however, this statistic includes the eDRAM logic to memory bandwidth, and not internal CPU bandwidths. The eDRAM internal logic to its internal memory bandwidth is 256 GB/s. The high bandwidth is used primarily for z-buffering, alpha blending, and antialiasing; it saves time and space on the GPU die. Between the eDRAM die and the GPU, data is transferred at 32 GB/s. The memory interface bus has a bandwidth of 22.40 GB/s and the Southbridge a bandwidth of 0.5 GB/s.

Audio and video All games made for the Xbox 360 are required to support at least Dolby Digital 5.1 surround sound. Sound files for games are encoded using Microsoft's XMA audio format. An MPEG-2 decoder is included for DVD video playback. VC-1 or WMV is used for streaming video and other video is compressed using VC-1 at non-HD NTSC and PAL resolutions or WMV HD. The Xbox 360 also supports H.263 and H.264 MPEG-4 videos. Unlike the original Xbox, voice communication is handled by the console, not by the game code, allowing for cross-game communication. There is no voice echo to game players on the same console; voice only goes to remote consoles.

Initially there were no digital video outputs such as DVI or HDMI on the Xbox 360; instead, HD-quality output could only be produced over component video (used by both the 3 RCA component cable and the Japanese D-terminal cable) and later VGA (via a software update). An HDMI port was introduced to the Xbox 360 by July 2007 with the introduction of the Elite model. A wide array of SDTV and HDTV resolutions are supported by the console hardware; up to 1080p after the October 2006 software upgrade. While most games are rendered natively at 720p, the video from all games can be scaled by the hardware to whatever resolution the user has set in the console's settings; from 480i NTSC and 576i PAL all the way to 1080p HDTV.

DVD storage

Xbox 360 is equipped with a 12× DVD drive, with a data transfer rate of 16.5 MB/s. The original production DVD drives were manufactured by LG, Samsung, and Sony. Beginning in November 2006, a new model the BenQ VAD6038 was introduced, which is said to run faster than the previous models and, in addition, is much quieter. There is a new drive by LiteOn.

Games are stored on standard 8.5 GB dual-layer DVD-ROMs; however initially only 7.3 GB (6.8 GiB) were allocated to be used for games on the "Xbox Game Disc 2" (XGD2) early format. With the XGD3 later format introduced in 2011, the usable space was brought up to 8.3 GB (7.8 GiB). This marked an increase in available space for games from 85% to nearly 98%. In both formats, the unallocated space for games is used for anti-piracy security software.

The option to apply a regional lockout to games is available to publishers, although DVD region codes are always enforced for movies. Microsoft has implemented methods to prevent hacking through the drive. Later drive models have the external debug triggering removed and black hard glue added to cover all the chip and controller pins. The drive is able to read both DVD±R and DVD±RW in addition to being able to play DVD-Video out of the box, unlike its predecessor, which required the purchase of an add-on remote. The system is also capable of playing standard CDs along with CD-R/RW, CD-DA, CD-ROM XA, CD-Extra, WMA-CD, MP3-CD, and JPEG Photo CD. Some users reported problems with the disc drive, as when a user changes the console's orientation, the inserted disc may brush against the drive's pickup assembly and incur scratches to it. The users manual advises against changing the console's position while there is a disc in the drive. Other users report experiencing disc scratching during normal horizontal usage.

Announced at CES 2006 and first publicly shown at E3 2006, an external HD DVD drive was released in North America on November 7, 2006 (for US$199.99) and in Japan on November 17, 2006 (for ¥19,800). In the UK, France and Germany, the HD DVD drive was released for €199.99/£129.99. The HD DVD drive was bundled for a limited time with an Xbox 360 Universal Media Remote, as well as an HD DVD copy of Peter Jackson's King Kong. The drive plays HD DVD movies, although all Xbox 360 games will remain on the DVD format. Microsoft had no plans to include an internal HD DVD player in future Xbox 360 designs. The drive connects to the Xbox 360 via USB and contains two integrated USB ports on the rear. Games can not be played on the HD DVD drive. Microsoft has since discontinued the HD DVD add-on since the format was officially dropped by Toshiba.

List of DVD drives Manufacturer(s)ModelFirmware version(s)NotesToshiba-SamsungTS-H943MS25MS28Hitachi-LGGDR-3120L003200360040004600470058005900780079FL/FKDL10N (Xbox 360 S)0500AAPhilips & BenQ (PBDS)VAD603862430C64930C 04421CNew FW after System Update 2.0.13146.0 version. (04421C)Philips & Lite-On (PLDS)DG-16D2S74850C83850C v183850C v293450C 02510CNew FW after System Update 2.0.13146.0 version. (02510C)DG-16D4S (Xbox 360 S)950402250401027210711214New FW after System Update 2.0.13146.0 version. (9504 → 0272)DG-16D5S (Xbox 360 S)A44511751532

Hard drive storage

The Xbox 360 uses standard 2.5" SATA hard disk drives (HDDs) held within custom enclosures. These units have a custom connector to facilitate connection to the Xbox 360 and the drives themselves feature custom firmware (making stand-alone drives incompatible). The drives are detachable, making it possible to move data from one console to another, and to upgrade the size of drive on a console. The hard drives themselves are manufactured by various companies, including Fujitsu, Seagate, Samsung, Hitachi and Western Digital. Certain Western Digital hard disk drives can be modified with a program called HDDHackr to be used with the Xbox 360.