A Brief Glimpse at Tonga
We won’t spend a whole lot of time on this’n, as the basic breakdown goes like this: imagine there’s two decks of cards in front of you, one called Tahiti, the other called Hawaii. You can only have a total of one full deck’s worth of cards on hand though, so how do you combine them together? You take the best cards from both decks, shuffle them together, and then you call it Tonga. At a slightly deeper level, what has happened is they took the value and already strong GCN architecture of the Tahiti core and added in various features that were only present on the R9 290/290X/260X.
The newly included features include Project FreeSync compatibility once the VESA standard is more widely adopted, AMD TrueAudio for more accurately produced directional sound in gaming, AMD PowerTune for managing heat better, and XDMA Crossfire which allows the card to CrossFire through the PCI-E bus rather than using those hideous copper-colored CrossFire bridges. Something that most gamers may not appreciate so much, but should be interested in, is the addition of H.264 4K video encoding. By incorporating this new decoding language, the R9 285 can have as much as a 47% performance improvement over GTX 760 when it comes to playing back 4K video in the correct environment. This makes this card an even better choice for HTPC users who want a lightweight, powerful graphics card that can also churn out 4K video without having to worry about inconsistent or otherwise poor video playback. It is a feature that even the mighty Hawaii core can’t claim to have.
Now before we move on to the real heart of the matter, I wanted to address the elephant-in-the-room: “dat memory bus.” We saw a fair amount of nay-saying floating around the inter-tubes regarding AMD’s decision to step back from a 3GB memory buffer on a 384-bit bus to a 2GB memory bugger on a 256-bit bus, a-la nVidia. Most are under the assumption that this will hinder gaming performance at higher resolutions, and in select scenarios those people may be right… but let’s consider for a moment that we are talking about what is ultimately a mid-pack GPU architecture: are you REALLY going to buy this card if you plan to play at 1440P, or are you going to go for a clearly more capable contender in the R9 290 or the GTX 970, which are also sitting at price points that more accurately reflect the size of the wallets of 1440P gamers? The other thing to consider is that they have improved color data compression (called Delta Color Compression), which equates to a 40% more efficient memory configuration than Tahiti. If this sounds familiar to you it’s because nVidia just announced similar technologies in their newest Maxwell lineup, they just called it something different and implement it differently. While we cannot validate these claims to better memory efficiency just yet, it will still be interesting to see what further iterations of the Tonga core will do.
Now we’ll take a quick look at Sapphire’s factory overclocked take on Tonga.