PCIe Gen 3 - ZeroCore Power - Eyefinity

PCIe Gen 3

All cards in the entire AMD Radeon series 300 range are PCI Express Gen 3 compatible which provides a 2x faster transfer rate than the previous generation, this delivers capabilities for the next generation of extreme gaming solutions. So opposed to PCI Express slots which are at Gen 2, the PCI Express Gen 3 has twice the available bandwidth and that is 32GB/s, improved efficiency and compatibility and as such it will offer better performance for current and next gen PCI Express cards. To make it even more understandable, going from PCIe Gen 2 to Gen 3 doubles the bandwidth available to the add-on cards installed, from 500MB/s per lane to 1GB/s per lane. So a Gen 3 PCI Express x16 slot is capable of offering 16GB/s (or 128Gbit/s) of bandwidth in each direction. That results in 32GB/sec bi-directional bandwidth. You do need a PCI-E 3.0 compatible motherboard and processor though. 

Power Consumption 

The R9-390X has a 250~275 Watt TDP (maximum power draw). AMD focused on idle states as well, when you are in desktop mode for example in the year 2008 on 55nm a graphics card would draw up-to 90 Watts. That changed dramatically on the 40nm nodes and products towards a much better ~20 Watts. A new precedent was being set with the initial R7000 launch though as in desktop idle mode the graphics cards only consume 2.7 Watts. So when the unutilised GPU is more than 95% it can shut almost 99% of itself down, even the ventilator fan will spin down and disable itself (which is a little freaky when you first see it really). So what's happening there you might ask? Well, as soon as the system goes into long idle state and applications are not actively changing the screen contents, the GPU enters the ZeroCore power state. In the ZeroCore power state, the GPU core (including the 3D engine / compute units, multimedia and audio engines, displays, memory interfaces, etc.) is completely powered down. ZeroCore Power state maintains a very small bus control block to ensure that GPU content is still visible to the operating system and BIOS. The enablement of the ZeroCore Power feature is controlled by the driver. The driver on its end monitors the display contents and allows the GPU to enter the ZeroCore Power state, in the condition that the GPU enters long idle and subsequent work requests are no longer being submitted to the engine. If any applications update the screen contents, ZeroCore Power technology can periodically wake the GPU to update the framebuffer contents and put the GPU back into the ZeroCore Power state. Furthermore, applications such as Windows 7/8 desktop gadgets are architected to minimize activity and save power in the long idle state. These applications are active during screen-on mode to display dynamic content such as weather, RSS feeds, stock symbols, system status, etc. but also have the intelligence to suspend any updates and activity when the system enters long idle. These applications will not wake the GPU from the ZeroCore Power state in long idle. I have immense respect for the new technology as it is a truly great achievement. So TDP wise, the R9-390X does push up-to 250~275 Watts when it peaks during gaming, but 2.7 Watts in idle.

Eyefinity

One of the biggest success stories of the Radeon series was the introduction of Eyefinity. Eyefinity allows you to use multiple monitors in desktop and gaming mode. Typically you needed the very same monitors and resolutions, Eyefinity 2.0 changes that. You are able to create custom resolutions these days. More monitor signal bandwidth is created with the Radeon HD 7000 / Radeon R7 and R9 series cards as well, you may create resolutions of 16k x 16k. This for a fact allows you to setup say five screens in 5.1 Landscape mode with 1920x1200, 2560x1600 and now even Ultra HD 4K 3840 x 2160 monitors. You guys are now starting to understand why the R9-280X has 3GB of graphics memory and the R9-290 series even 4 GB; huge resolutions require huge framebuffers. And for the above mentioned setup with 3840 x 2160 monitors that would boil down to 11520 x 2160 pixels, that's a 24 Mpixels resolution -- HUGE.