Originally Posted by Ultracarpet
Just curious as to some points brought up earlier about it having to be some sort of miracle for amd to beat the titan... as a rough estimate the titan is usually about ~30 percent faster than a 7970 right? so with 2x the rop's, 30% more shaders, 512 bit memory bus etc... how could it not compete? if the r9 290x has no core improvements over the 7970 at all, it technically speaking should trade blows with a titan no? So if you added any core improvements at all on-top of all these upgraded specs, which amd has had 2 years to do, it's just icing on top the cake when being compared to a titan. Like I saw alatar a while back saying gcn2.0 needs to be like 30 percent faster than 1.0 in order for the 290x to compete with the titan... I don't understand why that has to be. I would like someone to explain it to me.
Since no one else said it, I will.
Power is the thing. If AMD had 30% TDP headroom over the 7970GE then it wouldn't be any problem to hit Titan performance or beat it. The reality is though that 7970GE already has the same TDP as Titan. So they would need to get all that extra hardware to run with the same TDP without sacrificing clock speed.
Some people will counter that by saying "but look at the 7790, it brought 30% more fps with just 5% more power consumption". Yes, it did. And if you've read any R7 260X reviews, you'd know what happened when that 7790 needed to be pushed for any higher clock speeds: the power consumption went up significantly. "...overall performance per watt has actually dropped a lot. The HD 7790 delivered leading efficiency, but the R7 260X is now below the average when compared to the whole market. The good HD 7790 numbers in mind, I was a bit disappointed by the R7 260X's gaming power consumption." (source
). The same thing happened with 7970GE: the original 7970 was actually pretty good for performance/W, 7970GE much less so.
TDP limit is the reason why AMD has made Hawaii so massive. They couldn't go for higher clocks because GCN goes mental with TDP. They needed to lower
their clocks and the only way to get more performance with lower clocks is with a big chip running low voltage. The rumoured turbo BIOS thing seems like an indication that they've still had to push the clocks higher than they would have liked to. There most likely is very little extra to be had over those turbo clocks (last time they did this was 6990 which was tapped out). Another thing that might be a limiting factor is that Hawaii is extremely densely packed: the transistors/area is very high. Heat transfer gets more difficult when the heat source is more dense.
If I'm sounding too critical, then that's just the hype getting out of control. There are limiting factors for the Hawaii as well although it seems that some folks are taking any news as indication of world domination. I was sceptical that AMD would aim for Titan performance but the hardware seems to be aimed at just that. As of now, I'm thinking 290X will practically match the Titan at stock and with OC on stock BIOS since Titan is so strictly restricted, but Titan will have more headroom when those limits are removed. All in all, I'm really excited to see AMD doing a real monster chip!