On the other hand, GDDR5 is very pricey and in the end the trade-off doesn’t appear to have been worth it. There will be no GDDR5 support on Bald Eagle, either.
We can’t say we are surprised. GDDR5 makes sense in some settings and AMD’s custom console chips are a good example. However, in the consumer and server space there’s still no room for GDDR5 and this won’t change anytime soon.
Furthermore, GDDR5 really wouldn’t work well as system memory for more than obvious reasons. That means any GDDR5 Kaveri system would have to have a bit of GDDR5 soldered on the board, along with standard DDR3 memory slots. Such a system, with on-board GDDR5 and a big on-die 384-bit GDDR5 controller would be very expensive and tricky to produce and the added performance was clearly not worth it.
In theory, AMD could still do custom Kaveri parts with GDDR5, provided there’s a market for them, but we’re not sure there is.
More here.