Still GDDR5X needs less power for the same. And thats what I meant - and I'm pretty sure the others said the opposite, so I disagreed. What you do is basically speculating that Ram is doubled again on mainstream cards - what I'am not quite convinced will happen. 8 GB Ram is a lot, and I don't see weaker cards than a 390 running 8 GB of (GDDR5X) Ram. And even if they would, this has nothing to do with what I was talking about - doubling the amount and therefore increasing total power has nothing to do with the Ram type itself being more efficient than GDDR5, this is a moot point.
I didn't talk about HBM one bit. But you're still wrong, HBM has already proven itself on Fiji cards - it's a fact that they would be even more bandwidth limited without HBM, as overclocking HBM increased performance of every Fiji card further. This has proven that Fiji has not too much bandwidth, it has proven that it can't have enough bandwidth. Besides HBM made Fiji possible - there would be no Fiji without HBM. The same chip with GDDR5 would've taken more than 300 W TDP, a no-go, or would have needed a lower clock speed, which is a no-go too, because AMD wanted to achieve Titan X-like performance. The 275W TDP of Fury X was only possible with HBM on it. So not only DID the increased bandwidth help (a lot), it helped making the whole card possible at all.
Allow me a little exercise, and an apology. First, the apology. I conflated the quote from
@xorbe with what you said. It was incorrect, and my apologies for that.
Next, let's review the quotes.
Can you all not read? There's written on the presentation that it has reduced voltage, so power usage still goes down, not up - the straight opposite...
A very true point, yet somewhat backwards. Let's review the slides you criticize others for not reading. In particular, let's review 94a. The way that the memory supposedly doubles bandwidth is a much larger prefetch. That's all fine and dandy, but if I'm reading this correctly that means the goal is to have more RAM to cover the increasing prefetch. This would generally imply that more RAM would produce better results, as more data can be stored with prefetching accounting for an effectively increased bandwidth.
Likewise, everyone wants more RAM. Five years ago a 1 GB card was high end, while today an 8 GB card is high end. Do you really expect that trend to not continue? Do you think somebody out there is going to decide that 2 GB (what we've got now on middle ground cards) is enough? I'd say that was insane, but I'd prefer not to have it taken as an insult. For GDDR5X to perform better than GDDR5 you'd have to have it be comparable, but that isn't what sells cards. You get somebody to upgrade cards by offering more and better, which is easily demonstrable when you can say we doubled the RAM. While in engineering land that doesn't mean squat, it only matters that people want to fork their money over for what is perceived to be better.
... But you're still wrong, HBM has already proven itself on Fiji cards - it's a fact that they would be even more bandwidth limited without HBM, as overclocking HBM increased performance of every Fiji card further. This has proven that Fiji has not too much bandwidth, it has proven that it can't have enough bandwidth. Besides HBM made Fiji possible - there would be no Fiji without HBM. The same chip with GDDR5 would've taken more than 300 W TDP, a no-go, or would have needed a lower clock speed, which is a no-go too, because AMD wanted to achieve Titan X-like performance. The 275W TDP of Fury X was only possible with HBM on it. So not only DID the increased bandwidth help (a lot), it helped making the whole card possible at all.
To the former point, prove it. The statement that overclocking increases performance is...I'm going to call it a statement so obvious as to be useless. The reality is that any data I can find on Fiji suggests that overclocking the core vastly outweighs the benefits of clocking the HBM alone (this thread might be of use:
http://www.techpowerup.com/forums/threads/confirmed-overclocking-hbm-performance-test.214022/ ). If you can demonstrate that HBM overclocking substantially (let's say 5:4, instead of a better 1:1 ratio) performance I'll eat my words. What I've seen is sub 2:1, which in my book says that the HBM bandwidth is sufficient for the cards, despite its being the more limited HBM1.
To the later point, it's not addressing the issue. AMD wanting overall performance to be similar to that of Titan didn't require HBM, as demonstrated by Titan. What it required was an investment in hardware design, rather than re-releasing the same architecture with minor improvements, a higher clock, and more thermal output. I love AMD, but they're seriously behind the ball here. The 7xxx, 2xx, and 3xx cards follow that path to a T. While the 7xxx series was great, Nvidia invested money back into R&D to produce a genuinely cooler, less power hungry, and better overclocking 9xx series of cards. Nvidia proved that Titan level performance could easily be had with GDDR5. Your argument is just silly.
As to the final point, we agree that this is a low end card thing. Between being perfect for retread architectures, cheap to redesign, and being more efficient in direct comparison it's a dream for the middle range 1080p crowd. It'll be cheap enough to give people 4+ GB (double the 2 GB that people are currently dealing with on middle end cards) of RAM, but that's all it's doing better.
Consider me unimpressed with GDDR5X, but hopeful that it continues to exist. AMD has basically developed HBM from the ground up, so they aren't going to use GDDR5X on anything but cheap cards. Nvidia hopefully will make it a staple of their low end cards, so HBM always has enough competition to keep it honest. Do I believe we'll see GDDR5X in any real capacity; no. 94a says that GDDR5X will be coming out around the same time as HBM2. That means they'll be fighting to get a seat at the Pascal table, when almost everything is supposedly already set for HBM2. That's a heck of a fight, even for a much cheaper product.
