ATI Radeon HD 5830 Performance Preview

Radeon 5830 Reference Board

Now that they’ve got the Radeon 5600 and Radeon 5400 launches behind them, ATI’s filling in the few remaining holes in their DirectX 11 graphics lineup.

ATI’s addressing the most obvious hole they’ve yet to fill first, with today’s arrival of the Radeon 5830 slotting in the very important $200-$250 price bracket of the graphics market. Both ATI and NVIDIA have historically done lots of business in this segment, with previous sales champs like the GeForce 8800 GT and Radeon X1950 Pro doing quite well for both companies in the past, so it’s important that ATI’s finally introducing a new product here.

Judging by public reaction at the Radeon 5770 launch, a lot of enthusiasts have been holding out for an inexpensive DX11 card with a 256-bit memory interface to displace the Radeon 4870/4890 and GeForce GTX 260. With its 128-bit memory interface, the Radeon 5770 just couldn’t do that.

Nevertheless, as a member of the Radeon 5800 series family, the 5830 shares the same RV870 graphics core as the 5850 and 5870, and while it is a crippled derivative of those ASICs, it retains their 256-bit interface and GDDR5 memory.

Sounds perfect right?

5830 and 5850 reference boards

5830 reference board dwarfs the 4890 and 5850

If the performance is good, and the price is right, the 5830 would be the perfect solution for gamers on a budget. But as we just mentioned, ATI deactivates parts of the 5830’s Cypress LE graphics core. It features fewer stream processors than the Radeon 5870 and 5850, and runs at different clocks as you’ll see in this handy chart:

Radeon 5700/5800 Series Comparison
	Radeon 5770	Radeon 5830	Radeon 5850	Radeon 5870
GPU	Juniper XT	Cypress LE	Cypress Pro	Cypress XT
# of Transistors	1.04 Billion	2.15 Billion	2.15 Billion	2.15 Billion
Graphics Core Clock	850MHz	800MHz	725MHz	850MHz
# of Stream Processors	800	1120	1440	1600
Compute Performance	1.36 TeraFLOPS	1.79 TeraFLOPS	2.09 TeraFLOPS	2.72 TeraFLOPS
Texture Units	40	56	72	80
Texture Fill-rate	34 GigaTexels/sec	44.8 GigaTexels/sec	52.2 GigaTexels/sec	68 GigaTexels/sec
ROPs	16	16	32	32
Pixel Fill-rate	13.6 GigaPixels/sec	12.8 GigaPixels/sec	23.2 GigaPixels/sec	27.2 GigaPixels/sec
Z/Stencil	54.4 GigaSamples/sec	51.2 GigaSamples/sec	92.8 GigaSamples/sec	108.8 GigaSamples/sec
Memory Interface/Type	128-bit/GDDR5	256-bit/GDDR5	256-bit/GDDR5	256-bit/GDDR5
Memory Clock Speed	1.2GHz	1.0GHz	1.0GHz	1.2GHz
Memory Data Rate	4.8 Gbps	4.0 Gbps	4.0 Gbps	4.8 Gbps
Memory Bandwidth	76.8 GB/sec	128 GB/sec	128 GB/sec	153.6 GB/sec
Max Board Power	108W	175W	151W	188W
Idle Board Power	18W	25W	27W	27W

Notes

As you can see in the chart above, the Radeon 5830 ships with 1120 stream processors; six of RV870’s 20 SIMD units are disabled, leaving 14 active SIMD units. Rumors ahead of today’s launch predicted 1200 stream processors, so the final product is a little more crippled than initially projected.

When asked why so many SIMD units were disabled, product manager David Baumann put it bluntly: “Because of my yields”. Clearly when harvesting rejected Cypress Pro and XT chips to make the LE, ATI wanted to maximize their yields, throwing away as little as possible.

This helps to improve ATI’s bottom line, at the expense of performance.

ATI compensates for this by dramatically cranking up the clocks. As you can see, the Radeon 5830 runs at 800MHz core, 75MHz higher than the 5850 and just 50MHz shy of ATI’s flagship Radeon 5870. The board features the same 1.0GHz memory clock as the 5850 too.

But ROP count is down significantly, and as a result, the 5830’s pixel fill rate is nearly half that of the Radeon 5850.

One hand giveth, the other taketh away.

Because of the high clock speeds, the Radeon 5830 actually consumes more power at load than the 5850, despite the fact that the 5830 sports fewer shaders. Apparently RV870’s power consumption goes up pretty dramatically as you crank up the clocks.

In terms of pricing, ATI has set the 5830’s MSRP at $239. That’s pretty much in line with what we expected, and puts the 5830 roughly halfway between the 5770 and 5850, which start online at $160 and $300 respectively.