A look at the new Xbox 360 250GB's SoC: the first mass-produced CPU-GPU combo chip

By Abhinav Lal Published Date
26 - Aug - 2010
| Last Updated
26 - Aug - 2010
A look at the new Xbox 360 250GB's SoC: the first mass-produced C...

Hot Chips is certainly making calorie intake seem glorious, and apart from AMD showcasing their next gen Bulldozer and Bobcat processor technology, Microsoft showed off the new SoC (system-on-chip) processor of the new Xbox 360 250GB Slim Kinect-ready model. It’s a lot faster than the original processor, but that’s irrelevant, as latency had to be introduced to ensure identical speeds.

Manufactured with the IBM/GlobalFoundries 45nm process, Microsoft's new SoC is actually the first production desktop-class processor to combine a CPU, GPU, memory, and I/O logic onto a single piece of silicon, and is in homes ahead of AMD’s Fusion and Intel’s Sandy Bridge processors. The combination allows for better power efficiency, as well as much more inexpensive manufacturing due to fewer chips and heat management solutions, as well as a smaller motherboard and power supply unit. In fact, it’s 60% more power efficient than the original 90nm discrete CPU-GPU combination from 2005, with half the total silicon area.

The SoC reportedly took over 5 years to design, and has only 372 million transistors, a mind boggling figure when one looks at modern GPUs and processors. The new SoC contains a tri-core CPU, an ATI GPU, a dual-channel memory controller, I/O, and a new type of frontside-bus that’s on-die, instead of an easier internal connection. By using this on-die FSB, Microsoft has ensured there are no processor discrepancies between the old and the new Xbox 360 consoles, as it implements a latency and bandwidth that mimic exactly how the old system worked with discrete CPU and GPU processors, and effectively acts like an off-die FSB.

So while your Xbox 360 games won’t exactly run faster on the new architecture, the power efficiency of the console, as well as its manufacturing cost, would reduce. We hope that translates into a cheaper console at some point too.

Abhinav LalAbhinav Lal