RV730 - where are the 32 TMUs?
- Thread starter CarstenS
- Start date
Well yes but this is a wildly known error there. Plus, this is a "simple" error the overall structure of the chip is still correct.
Makes a lot of sense. Though I begin to wonder why it isn't faster than 3850 - it's got plenty of improvements, I guess it's just memory bandwidth limited?
Compared to rv670 it got:
- twice the TF units (granted they are simpler and with float formats they won't be faster than the rv670 half-as-many units), same amount of TA units
- half the amount of interpolators (16 vs 32)
- better (half as large) branching granularity
- half as many rop units, but probably doesn't really matter since z units have been beefed up so same amount of z tests, only color rops are really halved (and possibly only a quarter throughput in some fp16 render target cases?)
The pcgh results though indicate (scales almost fully proportional with memory clock in some cases with the simulated 4650) it could indeed be quite bandwidth limited. Well I guess that's not really a huge surprise for a card with such a low bandwidth / computational resources ratio...
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BW scaling @ Guru3D with mem-OC to 1225MHz:
http://www.guru3d.com/article/ati-radeon-hd-4670-review/13
It would be nice to see RV730 with GDDR5, but I have the feeling, that MC does not support it.
http://www.guru3d.com/article/ati-radeon-hd-4670-review/13
It would be nice to see RV730 with GDDR5, but I have the feeling, that MC does not support it.
Oh yes, looks like even the hd4670 scales very well indeed with memory frequency. Poor 4650 which has to work with half that...
Probably just not cost-effective in that market. At least from a pin count perspective, it should be possible (gddr5 requires some more pins than gddr3, but rv730 is larger than rv635), so it shouldn't be pad limited.
Jawed
Legend
RV740?
Something else RV730 appears to be missing is the CrossFireX Sideport, no surprise there.
Oh and RV670 has 32 interpolators:
http://forum.beyond3d.com/showpost.php?p=1193433&postcount=184
So it'd be no surprise if RV730 has a 2:1 interpolator:fragment ratio like its bigger brothers.
Oh and if people scan down the ixbt page you'll see plenty of TEX-dominated shader tests. If that isn't all the evidence needed for 32 TUs, then I don't know what is.
Jawed
The GPU core speed was also increased...
R300 also only has ~110 million transistors @ ~320 MHz.
Well it is more efficient since buffer compression schemes got better. It's probably got larger caches etc. too.
But as someone said, newer cards aren't so much about "more pixels" but rather "smarter pixels". The arithmetic part of a fragment shader doesn't really require any memory bandwidth...
Too bad yes. However only by 9% whereas memory increased by 23%, and the performance improvement (in this game) is a lot more than the core speed increase. But you're right this will (likely) play some part too.
What's even more interesting is that the 4670 manages to beat even a 2900 XT in COD4 at just about any settings, maintaining only a single fps difference @ 1920x1200 w/4xAA. Same for ET QW.
So 128-bit $80 card beats 512-bit $400 card. Yeah... I think we can go ahead and call the 2900 XT a bust now
So 128-bit $80 card beats 512-bit $400 card. Yeah... I think we can go ahead and call the 2900 XT a bust now
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Mintmaster
Veteran
The interpolator issue isn't much of a problem. Remember that with only 8 ROPs, at peak pixel throughput we have two Vec4 interpolators. Texture fetches sometimes use the same interpolator, and dependent fetches don't need any. Finally, even when you are interpolator limited (usually it only happens in old code written when interpolation ability was never an issue, as G80 would have changed the mindset of devs), you can still use the texture units for faster filtering.
As for BW, I'd expect the 4670 to be BW limited 40-50% of the time, i.e. a 20% mem overclock (without a core overclock) would net you 8-10% more fps. When you're building a budget card, though, there isn't much else you can do.
As for BW, I'd expect the 4670 to be BW limited 40-50% of the time, i.e. a 20% mem overclock (without a core overclock) would net you 8-10% more fps. When you're building a budget card, though, there isn't much else you can do.
Mintmaster
Veteran
It's a bit unfair to compare price due to the difference in launch dates. Still, the 4670 has fewer transistors and is 1/3 the size, which is a far greater reduction than 80nm -> 55nm would allow.What's even more interesting is that the 4670 manages to beat even a 2900 XT in COD4 at just about any settings, maintaining only a single fps difference @ 1920x1200 w/4xAA.
So 128-bit $80 card beats 512-bit $400 card. Yeah... I think we can go ahead and call the 2900 XT a bust now
More telling is RV635 vs. RV730. The latter is <25% bigger and on the same process too, but probably over twice as fast. ATI's low end was really crap last gen.
...and still very competitive to nVidias products (in price/performance, performance/watt and performance/square mm, too)
Yeah they priced them properly at least. But 2400/2600/3450/3650 really didn't offer performance that was worth paying for IMO. Their primary benefits were HDV playback and power consumption, but a gamer could easily pick a better card from the previous generation.
8600GT was a better card for gaming, even if it too was somewhat of a disappointment as a new mid-range card. Once 8600GT hit $100, I thought it became a pretty good deal in the market of 12 months ago or so. RV670 changed that eventually, of course.
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