AMD readying Radeon HD 6790 to take down GTX 550 Ti

by Navin Maini on 29 March 2011, 13:03

AMD's vineyard is reportedly preparing a concoction that is being oaked to outperform NVIDIA's GTX 550 Ti.

A derivative of the Barts architecture, the HD 6790 is rumoured to appear next week, with its blend based on the Barts LE platform.

The table below suggests many similarities between the upcoming Barts LE part and its vintage siblings - the Barts Pro based HD 6850, and Barts XT based HD 6870.

	HD 6790	HD 6850	HD 6870
GPU	Barts LE	Barts Pro	Barts XT
Node	40nm	40nm	40nm
Die size	255 mm2	255 mm2	255 mm2
Transistors	1.7 Billion	1.7 Billion	1.7 Billion
SM units	10	12	14
Stream processors	800	960	1120
GPU frequency	840 MHz	775 MHz	900 MHz
Performance	1.34 TFLOPs	1.5 TFLOPs	2.0 TFLOPs
Texture units	40	48	56
Texture fillrate	33.6 Gtexel/s	37.2 Gtexel/s	50.4 Gtexel/s
ROPs	32	32	32
Memory type	GDDR5	GDDR5	GDDR5
Memory buffer	1GB	1GB	1GB
Memory frequency	1050 MHz (4200MHz)	1000 MHz (4000MHz)	1050 MHz (4200MHz)
Bus width	256-bit	256-bit	256-bit
Bandwidth	134.4 GB/s	128 GB/s	134.4 GB/s
Power connectors	2 x 6-pin	1 x 6-pin	2 x 6-pin
Power consumption	19/150W	19/129W	19/151W

Marrying up 10 SM units and 800 stream processors, it is believed that the GPU will muster up an 840MHz core speed, tying in with 1GB GDDR5, running at 1,050MHz (4,200MHz effective).

The claimed TDP of 150W has already raised eyebrows, as suggested specifications indicate that whilst underperforming when compared to the HD 6850, the HD 6790 is expected to have increased power requirements.

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It's a salvaged barts core with higher voltage, that's why it has a 150W TDP. AMD did the same thing with the 5830, remember it had a higher TDP than the 5850 whilst being a lot slower.

In this case, the card should be a bit closer to the 6850 as it still has a full complement of ROP's, which was the big failing of the 5830 (it had halved ROP's).

If it's aggressively priced it could make a decent mid range budget card.

Given that the shader core is almost identical to a 5770 it's going to have to hope the ROPs and memory bandwidth make up enough ground: which would then go to show that they mis-engineered the 5750 / 5770 to be back-end bottlenecked. Technologically, I don't see a way this can turn out well for AMD ;) It'll also be interesting to see how it compares to the 6850, since it has less shaders but higher core and memory clocks. It should lose ~ 9% in raw throughput,so it should still be slower, but it looks like it could be pretty close…

Financially it's going to be a tough sell too, as it'll have to slot in somewhere between £110 and £135, landing in GTX460 territory: so it's not just going to have to beat the GTX550, it's going to have to beat those as well. And it's going to have to do it while justifying the premium over the 5770 but without stepping on the 6850s toes. Tricky balancing act…

The power consumption does not look good TBH.

Both the HD5830 1GB and HD6870 1GB have the same number of shaders but the HD5830 runs them at 800MHZ and the HD6870 1GB at 900MHZ. However,the HD6870 has 32 ROPs. The RAM on the HD6870 only runs 50MHZ higher too.

However,the HD6870 1GB is over 30% faster than an HD5830 1GB:

http://www.techpowerup.com/reviews/HIS/Radeon_HD_6870/29.html

I suspect that the HD6790 1GB will probably be similar in speed to an HD5830 1GB:

http://www.techpowerup.com/reviews/HIS/Radeon_HD_6850/28.html

Something tells me the table isn't quite right. :)

It is not that difficult to slot in. A 5770 is £80-90, a 6850 £130-£140. Price this at £110-£120 and you will be ok.

I think the 550ti will be the even a more difficult sell … nVidias midrange is really only sustained by the 460.

AMD readying Radeon HD 6790 to take down GTX 550 Ti

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