by Anton Shilov
03/05/2013 | 06:02 AM
Even though Advanced Micro Devices’ Fusion accelerated processing units have featured advanced graphics cores for years, their performance was limited due to insufficient memory bandwidth. With the next-generation high-performance APU code-named Kaveri, AMD will finally unleash its Radeon HD’s potential thanks to a secret weapon, 128-bit GDDR5 memory controller.
AMD Fusion A-series APU code-named Kaveri is projected to feature up to four Steamroller high-performance x86 general-purpose cores as well as GCN architecture-based AMD Radeon HD 7000 graphics engine. However, the most unexpected feature of Kaveri will be its 128-bit memory controller, which will support both DDR3 as well as GDDR5 memory, according to the BrightSideOfNews web-site. The latter memory type should enable very high performance of integrated graphics sub-system for all-in-one and mobile systems.
Maximum memory bandwidth provided by dual-channel DDR3 memory sub-system at 1866MHz is 29.8GB/s, which should be sufficient for today’s microprocessors, but may be insufficient for powerful graphics adapters. By contrast, an inexpensive 128-bit GDDR5-based memory sub-system with 3400MHz effective clock-speed enables 54.4GB/s of memory bandwidth, or 82% higher compared to DDR3-based subs-system. While this clearly is not enough for a high-end graphics solution, it should be sufficient for modern mainstream graphics adapters that cost $100 - $130 and which truly provide adequate performance in video game.
There are two problems with GDDR5 memory: it requires point-to-point interconnection and the maximum capacity of today’s GDDR5 chips is 2Gb (256MB). The former fact means that AMD A-series “Kaveri” APUs with GDDR5 memory will come in BGA package and will be soldered to mainboards, which will not be a problem for notebooks and all-in-one desktops, but will eliminate any possible upgrade options. The latter fact means that either AMD Kaveri-based system will be equipped with maximum of 4GB of GDDR5 (as 8GB of GDDR5, like on the PlayStation 4, requires 32 chips), which is not enough for modern general-purpose PCs, or AMD and its partners will have to wait till 4Gb GDDR5 chips arrive.
It is expected that AMD will release its Fusion A-series “Kaveri” APUs will be released in late 2013. However, it is unclear whether AMD will be able to roll-out its next-gen APUs in mass quantities or will only formally unleash the new accelerated processing units.
AMD did not comment on the news-story.