AMD 890GX Chipset Review - SATA 6G goes native
The AMD 890GX
The first thought that most people had with the AMD 890GX is that it would be the first DirectX 11 integrated graphics chip. Unfortunately, that is not true. The graphics portion of the chip is still based on the RV620, the same overall design which powered the AMD 785G. This is not necessarily bad, as it is still the only DX 10.1 integrated product on the market. It is now branded as the HD 4290 graphics chip. It shares the same 40 stream units (which comprise 1 SIMD unit), 4 ROP units, and 8 texture address units. AMD did throw users a nice bone though. The unit is clocked at a nice 700 MHz, vs. the 500 MHz of the 785G. This speed increase comes with a very small TDP increase due to a redesign to the chip. AMD is also allowing the pairing of a HD 5450 with the 890GX, which should give a decent boost in overall performance. This will of course limit the HD 5450 to DX10.1 instead of the full DX11 functionality that it natively has.
The overall topology of the new chipset. Note the Alink Express III connection and the SATA 6G support.
The video playback portions of the chip are still fairly impressive. It sports essentially two AVIVO HD units, so two full 1080p playback streams are supported at once. It leverages the stream units to provide good de-interlacing support, though Vector Adaptive de-interlacing is likely too computationally intensive for the 40 stream units the 890GX sports. Playback is still very good regardless, and CPU usage for Blu-ray playback is minimal. Unfortunately, since the chip was not massively redesigned using the HD 5000 series of chips, it still does not support bitstreaming of HD audio codecs, much less 8 channel LPCM. Users are stuck with Dolby Digital 5.1, DTS, and 2 channel LPCM when it comes to HDMI audio on this chipset.
It may not be "incredible", but it certainly is serviceable!
The big push with the AMD 800 series of chipsets is the native SATA 6G support. AMD is the first to release a native implementation of SATA 6G, and look to be a full year ahead of Intel in terms of support. A lot of people (including myself) were quite excited that AMD was going to include SATA 6G support, as well as fix a lot of the current AHCI and performance issues that their southbridges have suffered from.
AMD also wants to really push USB 3.0 support, but that functionality is not native to the SB850 southbridge. Instead, AMD will rely on the NEC USB 3.0 controller to be bundled into upcoming motherboard designs, and the majority of them will feature this USB 3.0 functionality. Something that AMD is quite proud of is the implementation of PCI-E 2.0 when integrating all of these features. The USB 3.0 controller uses 1 x PCI-E 2.0 lane, which features 1 GB/sec of bidirectional data (500 MB/sec upstream + downstream). This should be able to handle the theoretical 480 MB/sec of bandwidth USB 3.0 supports.
AMD is not holding us back in terms of interchip bandwidth when it comes to high speed peripherals.
AMD also upgraded the 2 x PCI-E 1.0 lanes from the SB750 to full 2 x PCI-E 2.0 lanes on the SB850. This again should allow full bandwidth for SATA 6G speeds. The 2 GB/sec of aggregate bandwidth should be able to handle the data streams of several of the fastest drives in RAID configurations.
This is something that AMD has over the latest H55 and H57 chipsets from Intel. While the i7/i5/i3 mainstream processors all feature PCI-E 2.0 support from the CPU, their accompanying chipsets only feature PCI-E 1.0. This means that any PCI-E slot that does not include the PCI-E Graphics slot is 1.0, and all accompanying chips which use a PCI-E lane for communication is limited to PCI-E 1.0 speeds. When it comes to SATA 6G and USB 3.0 controllers, both can easily saturate a 1 x PCI-E 1.0 lane if connected to a fast device. We are essentially talking SSDs here.
While the northbridge portion is nice in that users have all that extra performance that 200 MHz affords, the real star is the SB850 southbridge. Now we must question if AMD has exorcised all of its performance demons when it comes to designing southbridges.
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