Summary: Thanks to its 320 shaders ATI's Radeon 4670 is capable of giving the Radeon 3850 a run for its money at significantly lower price tag: just $80. As a result, NVIDIA's countered with price cuts for the 9600 GSO and 9600 GT. See how the 4670 compares to all of these GPUs in this article!
Their RV770-based Radeon HD 4850 and 4870 both deliver excellent performance in their respective price segments. Their arrival forced NVIDIA to slash prices on their entire GeForce lineup, including their flagship GeForce GTX 260 and GTX 280 GPUs. Despite the GeForce price cuts, this hasnít stopped ATI from taking share from NVIDIA. And in the high-end of the market, ATIís dual GPU Radeon HD 4870 X2 is the fastest graphics card in the world right now.
But how well does this strategy scale down? Does ATIís architecture continue to perform well with half of its functional units (including its shaders), removed? Thatís what weíre here today to find out!
Finally, a new ATI GPU architecture for the mainstream segment
Based on ATIís RV730 GPU, the Radeon 4600 series is designed to replace the Radeon 3600 series in ATIís lineup. Despite their new name, the 3600s werenít dramatically different than ATIís older Radeon 2600 line. The Radeon 3650ís RV635 GPU boasted the same 120-shader architecture as the Radeon 2600, with 8 texture units, 4 ROPs, and a 128-bit memory interface, just like Radeon 2600. The big additions ATI incorporated into RV635 were DirectX 10.1 support and a more energy efficient 55-nm manufacturing process. Every where else the Radeon 3600 GPU was quite similar to its predecessor, and as a result, performance between the two was quite comparable. As you can imagine this put ATI at a performance disadvantage in comparison to NVIDIAís GeForce 8500 and 8600 lines of GPUs.
To accomplish this ATI has dramatically reduced the number of shading units inside RV730. While RV770 boasts up to 800 stream processors, just 320 stream processors are found within RV730. Interestingly enough, this is the same number of shaders found in ATIís previous high-end architecture, RV670/R600.
As a result there are cases where the Radeon 4670 comes awfully close to matching the performance of Radeon 3850, if not outperforming it, but more on this later.
In comparison to RV770, ATI has adjusted the arrangement of the SIMD cores. RV730 ships with half the number of stream processors per SIMD core, just 40 shaders in RV730 per SIMD core versus 80 shaders per core in RV770. RV730 boasts 8 SIMD cores total, resulting in a grand total of 320 stream processors (40 stream processors per SIMD core x 8 SIMD cores). Like RV770, each SIMD core in RV730 has four dedicated texture units bringing the total number of texture units to 32 inside RV730.
If you recall, texturing was a huge shortcoming in ATIís previous generation architecture. RV670 supported just 16 texture units. So RV730 has two times the number of texture units as ATIís previous generation high-end architecture, and four times the number of texture units as its direct predecessor, the Radeon 3650. Like RV770, RV730ís texture units have also been redesigned to deliver up to two times the texture cache bandwidth of RV670.
The ROP subsystem has been improved as well. RV730 sports 8 ROPs. Thatís two times the number of ROPs as RV635. ATI has also tweaked the ROPs to provide double the AA fill-rate for 32-bit and 64-bit color as well as double the peak rate for depth/stencil operations. These improvements allow the RV730 to perform quite competitively with the Radeon 3850 despite its memory bandwidth disadvantage: 32GB/sec in Radeon 4670 versus 57.6GB/sec in the 3850.
Speaking of the memory interface, we should mention that like other mainstream card offerings itís 128-bit wide, so no change there in comparison to RV635. However, ATI clocks the memory on the Radeon 4670 up to 1.0GHz (2.0GHz effective), yielding 32GB/sec of peak memory bandwidth. The Radeon 3650 topped out at 25.6GB/sec.
RV730 continues to rely on TSMCís 55-nm manufacturing process, with the chip containing approximately 514 million transistors. Each RV730 chip sports a die size of just 146 square millimeters with a max TDP of 59W for the Radeon 4670, and 48W for the Radeon 4650.
As we just mentioned, ATI will be offering two different GPUs based off RV730: the Radeon 4670 and the Radeon 4650. Digging deeper, ATI will be offering multiple 4670 and 4650 configurations, with memory sizes ranging from 512MB of GDDR3 graphics memory up to 1GB of DDR3 for the 4670, while 512MB and 1GB SKUs for the 4650 will also be provided. The following chart summarizes ATIís 4600 series lineup:
As you can see, ATI will be shipping the 4670 with GDDR3 and conventional DDR3 memory types. Weíve been told that latency between the two memory types should be the same, however AMD uses GDDR3 on the 512MB model because it supports 8-bit burst and also 1GHz DDR3 modules are more expensive. Instead ATI relies on 900MHz DDR3 for their 1GB Radeon 4670 boards.
With a max board power draw of just 59W, the Radeon 4670 gets all its power from the PCIe interface, no external power connector is needed for operation. The board design of the card itself is quite simple, and the boardís PCB measures just a hair over 6.5Ē.
ATI continues to outfit the reference board design with two dual-link display outputs. HDMI and DisplayPort are also supported by the GPU as well, so conceivably weíll see cards from select ATI board partners touting these display capabilities at some point in the near future. The Radeon 4600 series also supports integrated 8-channel digital audio natively over DisplayPort and HDMI. With GeForce GPUs a passthru cable must be connected from your graphics card to your sound card in order to pass audio over HDMI, so the Radeon 4600 card eliminates the hassle of connecting that cable.
GeForce 9600 GSO
To counter the Radeon 4670, NVIDIA is dusting off an old GPU we assumed was on its way to the boneyard for retirement: the GeForce 9600 GSO.
Fortunately this is where the cuts end for the GeForce 9600 GSO. NVIDIA uses the exact same reference board design and cooling originally used on the GeForce 8800 GT from last year for the 9600 GSO. While the original 8800 GT cooler was notorious for running hot, NVIDIA improved the cardís fan, making it slightly larger than the original cooler. This has a profound impact on temps and noise, and fortunately this is the exact same fan used for the 9600 GSO.
Officially the GeForce 9600 GSO is positioned between the GeForce 9500 GT, which is priced between $59-$69 and the 64-shader GeForce 9600 GT, which is now priced at $99.
With an MSRP of $79, the GeForce 9600 GSO is priced to take on the Radeon 4670 directly, and while itís based on NVIDIAís 65-nm G92 GPU today, NVIDIA has confirmed that like the GeForce 9800 GT, the 9600 GSO will soon be making the transition to 55-nm. 55-nm is in full production today, so expect to see 55-nm GeForce 9600 GSO boards based on NVIDIAís G92b GPU hit the market in the weeks ahead.
Intel Core 2 Duo E8600
4GB OCZ Platinum DDR2-1333
GeForce 9800 GT
GeForce 9600 GT
EVGA e-GeForce 9600 GSO
GeForce 9500 GT
ATI Radeon 4650 512MB
ATI Radeon 3850 512MB
ATI Radeon 4850 512MB
300GB Western Digital Caviar SE
Windows Vista Ultimate 64-bit w/Service Pack 1
Company of Heroes 1.71
Game Settings Used
Crysis High Ė Direct3D
We maxed out the sliders in Catalyst Control Center when OCíing the 4670. 800MHz core/1050MHz memory was as far as ATIís driver team letís us go at this point.
With todayís introduction of the Radeon 4670, you not only get a very inexpensive GPU priced at just $79, you also get a card thatís capable of dishing out very good performance for its intended segment of the graphics market. In some cases the 4670 outran ATIís Radeon 3850 in our testing! The card also scaled quite nicely when going from one to two cards for CrossFire (Crysis being the only exception).
This is all made possible thanks to its 320 shader architecture and improved texturing horsepower (among other things, ATI has quadrupled the number of texture units in RV730 when compared to RV635), not to mention the tweaks ATI has made to their ROP subsystem for the R7xx generation of GPUs.
All these enhancements allow the GPU to pack quite a bit of punch for a card that relies on a simple 128-bit memory interface.
DX10 games like Crysis, Company of Heroes, World in Conflict, and Devil May Cry 4 ran quite well on the 4670. In Crysis the card was just 10% slower than the Radeon HD 3850 at 1600x1200, delivering a playable 40 fps when using the gameís medium settings. In Devil May Cry 4 and Company of Heroes the 4670 narrowed that gap to just 6% at the same resolution with 4xAA. The Radeon 4670 actually outran the Radeon 3850 in our testing with HL2 Episode Two. The only test where the Radeon 3850 consistently pulled ahead of the 4670 by double digit margins was BioShock DX9 with 4xAA.
NVIDIAís GeForce 9600 GSO is a formidable competitor to the Radeon 4670 however. In our tests the cards traded the performance crown several times, with games like Devil May Cry 4, Episode Two, and Quake Wars running faster on the Radeon 4670, while the 9600 GSO pulled ahead of the ATI card in Crysis, Company of Heroes, BioShock, Call of Duty 4, and Lost Planet (which uses the same game engine as Devil May Cry) all running faster on the 9600 GSO. World in Conflict and Oblivion were basically a draw.
Overall the GeForce 9600 GSO was a little bit faster than the Radeon 4670, but it wasnít by much.
Of course, the Radeon 4670 is considerably cheaper for ATI to produce than GeForce 9600 GSO is for NVIDIA. NVIDIAís basically selling their $150 9800 GT chips in $79 boards, while ATIís architecture is purpose built for the sub-$100 market, sporting a much smaller die (146 square millimeters in RV730 versus G92ís 330 square millimeters) and a less complicated PCB design. The 4670 also has a power advantage over the GeForce 9600 GSO as well.
The only real tweak weíd like to see ATI implement is a slightly faster, or a slightly larger fan. The Radeon 4670 doesnít run as hot as the Radeon 4850, but it sure would be nice if the card ran another 10 degrees cooler than the reference board design does today.
Which card would we pick if it were our money? Thatís a really tough question thatís ultimately going to boil down to which games you play, and the application you plan on using the card for. In our opinion the Radeon 4670 would be the perfect choice for HTPC use thanks to its diminutive size, native audio over HDMI, and low power consumption. Weíd probably pick up a card that integrates a better cooler than the ATI reference design though.
The GeForce 9600 GSO ever so slightly gets the overall edge in gaming, with PhysX support as icing on the cake. We still havenít had an OMG PhysX moment, but with games like Brothers In Arms: Hellís Highway, Borderlands, and Mirrorís Edge shipping between now and January 2009, we may finally see a compelling PhysX game soon. ATI will of course counter with DirectX 10.1 support. So far three titles have been confirmed: the RTS Battleforge from EA/Phenomic, SEGA's RTS Stormise, and NHN Games RPG Cloud 9.
NVIDIA had better not take ATI for granted anymore though. The Radeon 4000 series has put ATI back on the map; theyíve now got a very compelling GPU at multiple segments while NVIDIA is basically forced to slash prices on existing products in order to remain competitive. This is having an awful effect on NVIDIAís margins and until they can respond with a new architecture of their own theyíll continue to suffer: while ATI has room to trim 4670 prices even further, NVIDIA really canít afford to go any lower. Theyíre practically giving the GeForce 9600 GSO away at cost as it is.
This is the conundrum NVIDIA is in, and until they can work their GeForce GTX technology down to lower price points, theyíll have to continue to rely on previous generation G9x parts like the 9600 GSO. Interestingly enough, this is exactly why ATIís abandoned the monolithic GPU. Perhaps NVIDIA may have to follow suit as well?
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