The SGI O2

 General Information


The SGI O2 is a nice allround-computer. It doesn't offer the power of an Octane, but it has more features at a lower price than an equally equipped Octane. Especially the O2 has hardware textures, a feature that can only be achived on Octanes or Indigo²s by adding expensive TRAM.

Graphic Options

Actually there is only one graphic option: The Cobalt graphics. It is a UMA system (uniform memory architecture) and uses the standard main memory as frame buffer and texture memory. This technique has both an advantage and disadvantage: There is virtually no limit for textures, but the framebuffer, texture memory and CPU have to share bandwith. But as a matter of fact, this system really can compete with an Octane MXI, especially in cases with complex geometry, the O2 seems to be faster than an Octane. The same is true for scenes with lots of textures - an Octane would have to swap all textures in and out of texture memory whereas the UMA architecture does not need to move textures around before using them.

The O2 is different from most other SGI boxes in one point: It usesa standard VGA connector (and no 13W3!) for monitor output, so you can use any good PC monitor that is capable of 'Sync on Green'.

There is also a special addon available for using the very special 1600SW SGI flatpanel.

Processor Options

Although the O2 mainly is a 32bit architecture, there are plenty of processor options avaiable ranging from an R5000 to an R12000.

Processor Speed L2 Cache
R5000PC 180 Mhz none
R5000SC 180 Mhz 512KB
R5000SC 200 Mhz 1MB
R5200SC 300 Mhz 1MB
R10000SC 150 MHz
175 MHz
195 MHz
225 MHz
250 MHz
R12000SC 270 MHz
300 MHz
R12000SC 400 MHz 2MB
RM7000A 350 Mhz 256KB

Note that you cannot simply upgrade from a R5x00 system to a R1x000 system by changing the CPU module, you also have to change the motherboard plus have to modify the case of the O2, because the R1x000 modules have a much bigger heat sink.

Note that there may be some systems with a R5000SC CPU running at 200 MHz but with only 512KB of cache - this is simply a sign that the CPU has been overclocked, as there never existed such a system from SGI.


The O2 uses custom memory modules - they can be found from time to time on ebay, but are rare and expensive. They are special 278pin DIMMs. Each bank consists out of 2 modules and the O2 has a total of 4 banks, that is 8 memory slots.


An O2 just needs a standard PS/2 keyboard and mouse (of course there are special gray keyboards and mice from SGI available) and has standard sound input/output connectors plus a 100MBit fullduplex ethernet connector. The only item you have to care about is the monitor: Although O2s have a standard VGA connector, the monitor has to support "sync-on-green" - although most modern PC Monitors support this method, you should assure that it really does by reading the manual before plugging it to an O2.

Video and Audio Options

All O2s either have a simple audio module or an audio/video-Module. The later one has video input/output connectors plus a special connector for a special O2-camera. You can simply upgrade an O2 without an A/V module by exchanging the module. You even don't need to open the case for this upgrade, it is really simple!

A Nice Case-Mod

So Case-Modding also started on SGI boxes. I am proud to present you a case mod that lets your O2 emit decent blue light.

My O2

Currently I own one O2.