Now with a new southbridge (SB600)!

• ATI CrossFire Xpress 3200 chipset (RD580 Northbridge and SB600(IXP600) Southbridge)

As confirmed by our synthetic and practical tests, the new AMD platform with DDR2 support and Socket AM2 definitely puts in for favorable attention from high-end users and overclockers. NVIDIA has met the announcement armed at all points, with a new series of nForce 500 chipsets. The company has found a lot of fresh arguments to attract attention of technically-oriented audience again. But it turns out that ATI is not going to put up with its second-fiddle role on the AMD64 chipset market (28% of the market). One of its steps to improve the situation is to perfect its high-end solutions.

Why didn't ATI become the first in this sphere? There are two objective reasons. As the division into SLI and CrossFire segments does not allow to use video cards on motherboards with competing chipsets, the choice of an extreme motherboard depends directly on the choice of a graphics system. But ATI has offered a mass ultimate CrossFire solution only recently - with the release of Radeon X1900XT (it's no secret that for various reasons all its previous solutions were just transition models and could attract only the most loyal fans of the Canadian manufacturer).

The well-known functional lag of ATI chipsets from NVIDIA (support for advanced SATA RAID modes, integrated network options), especially on motherboards with ATI southbridges, did not contribute to popularity of high-end solutions from this company either. Compatible southbridge from ULi had a serious drawback — it was manufactured by the company that actually belonged to a competitor.

But it's not hard to guess that both drawbacks were not insuperable. An attractive CrossFire solution was still launched. And in the very beginning of summer (strictly according to the announced dates) ATI has presented a new southbridge — SB600.

SB600 Southbridge Specs

• SATA-II AHCI controller (backward compatible with IDE) for 4 x SATA300 (up to 3 Gbit/s)
• RAID support for all SATA ports: 0, 1, and 1+0
• One PATA channel for two ATA133 devices
• 10 x USB 2.0 (no one has supported 10 ports so far, but NVIDIA)
• PCI bus (up to 6 bus master devices)
• A new standard of the HD Audio system
• AC-Link interface to connect AC’97 (2.3) audio codecs and MC’97 modem

Of course, SB600 should not necessarily be used only on motherboards with ATI CrossFire Xpress 3200. This southbridge can become a good partner to more democratic northbridges. At least from the technical point of view: like in all ATI Xpress chipsets, PCI Express is responsible for the northbridge link; a number of lanes can vary depending on requirements — 1, 2, or 4.

ATI SB600's functionality qualifies for the high-end level without any reservations. There is no support for peripheral PCI Express. It's just a peculiarity of chipsets from this company, as PCI Express support is a responsibility of the Northbridge. SATA — not maximum possible (for example, there is no RAID 5), but it's still excellent. PATA — unfortunately, it's on a par with competing products: there is only one channel for two devices. We've already mentioned 10 USB ports, HDA support is taken for granted (but its lack would have aroused severe criticism!). The only moot point is the network controller: SB600 just lacks it. The train of thought of most chipset manufacturers is crystal clear: the speed of a gigabit network adapter is not limited by PCIEx1 interface, so a cheap external controller will hardly be worse than an integrated solution. Only NVIDIA is going up stream, but its system is enhanced with additional features that provide other advantages.

Several words about the series

A series of ATI chipsets for Socket AM2 includes well-known CrossFire Xpress 3200 (RD580) northbridge with a couple of full-speed PCI Express x16 ports. Press materials stress that all PCI-E lanes, necessary for both ports, are in northbridge, while NVIDIA has them distributed between northbridge and southbridge. This setup promises more efficient interaction of video cards via the interchip Xpress Route bus. However, this solution has no chances, until ATI gives up the external link between video cards with a W-shaped cable in high-end sector.

Well-known CrossFire Xpress 1600 (RD480), previously known as Xpress 200 CFE, with switch-selectable PCI Express x16 configuration ("x16+x1"/"x8+x8") belongs to the group of systems with two video cards of entry level and "CrossFire Ready" (with a single video card to be supplemented in future). Note that 3000-series chips are manufactured by the 0.11-micron process technology, while Xpress 1600 is still 0.13-micron.

There will be a reinforcement in the medium-budget segment: the new 3100 chipset with unrivaled functionality features the x16+x8 mode of graphics ports. However, as we have already found out, NVIDIA nForce 570 SLI can also use this solution, it's currently limited for marketing reasons. So with the appearance of Xpress 3100 we can expect either a launch of a stand-alone modification of nForce 570 or even unlocking additional lanes for the existing model on the level of drivers and/or BIOS.

Motherboards with integrated video ($50 and higher, according to the official announcement) retain the old RS485 bridge, which is now called Radeon Xpress 1150. However, we didn't expect any new products here. It should be noted that we haven't found a discrete chipset without CrossFire support in the official list of chipsets for Socket AM2.

Reference motherboard on ATI RD580 + SB600

Reference motherboards from ATI has been looking suspiciously like the famous Pure Innovation series from Sapphire for some time. We must admit that it's the right move — a top chipset must be represented by a model motherboard. Moreover, the announcement of a corresponding model from Sapphire may prove that we didn't examine this engineering sample for nothing :)

There is no point in describing the layout of an engineering sample, but some issues are worthy of attention. Firstly, ATI engineers decided to add another four connectors to the four SATA connectors with sterling support for Serial ATA 2.0 (the pride of the new southbridge!) They will be supported by two identical Silicon Image controllers! Why so many? Why equip a desktop motherboard (even if a top model) with 6 and more SATA ports? I haven't heard a clear answer to this question from chipset/motherboard manufacturers. I suspect that this absurd solution (I hope it won't be used in production-line motherboards) should help ATI push reviewers to express their doubts about the necessity of multiplying SATA connectors.

At the same time, the tendency to reduce the number of supported ports to one, vexatious for owners of expensive IDE devices, also touched motherboards on ATI chipsets. Following the example of nForce 500 models, the new southbridge from ATI also supports only one channel.

Thermal conditions of the motherboard are again (for motherboards on ATI chipsets) very nice. The upgrade to 0.11-micron process technology completely makes up for the expanded functionality of the chipset. We can forget above active cooling even for elite models. Heatsinks on both bridges are getting rather hot, of course. But the key factor in designing cooling systems is not temperature as such, but the amount of heat dissipated by an object (dissipated power).

Convective heat transfer of a passive cooler directly depends on the temperature difference between a heatsink and environment. Hence, in case of low-power heat sources, instead of reducing the environment temperature (for example using forced ventilation), you can just as well use a symmetric approach — to expand temperature limits of a chip and let a heatsink get hotter. The hotter is the heatsink, the more difficult it is to raise its temperature by another several degrees, as its heat emission grows high. This very approach is increasingly often used by designers of chips for motherboards and video cards. Maximum permissible temperature for chips without losing stability reaches 80—90 degrees.

Nevertheless, a heatsink on field-effect transistors in a power circuit is always welcome. Reducing temperature is certainly useful here to get output signal of the highest quality (note that in this case heatsinks honestly cover all field-effect transistors in a CPU power circuit, not just a part of them, which is the most convenient to cover). As a result, the 4-phase switching voltage regulator of the processor incorporates four field-effect transistors per channel, six 3300 uF capacitors from Rubycon, and several ones of a lesser capacitance from Sanyo (an excellent choice!) The board contains a 8-pin CPU power connector of the server standard - EPS12V (4 pins +12 V). But in our configuration the motherboard was stable even with a popular 4-pin ATX12V connector. There are also two standard 4-pin peripheral connectors for additional power supply to PCIE video cards. Our tests demonstrate that even a single video card should be connected to this power source, as it raises stability of an overclocked system (it may also be a peculiarity of our sample). There are no empty seats on the PCB, there is just no backup BIOS chip. Motherboard dimensions — standard ATX (305×245 mm). It's not designed to be mounted into a PC case: like all reference motherboards from ATI, this sample has plastic feet on the bottom surface to make testing more convenient.

System monitoring (ITE IT8712F-A, according to BIOS Setup)

• Voltages on a processor, northbridge (general and Vcc) and southbridge, HT and PCI-E buses, battery, Vtt SUS, Vdd SUS
• RPM of 3 fans (the BIOS version we used in our tests displayed only rotational speed of the northbridge fan)
• CPU and board temperatures (by the corresponding embedded sensors)
• Automatic Mode — automatic control of the rotational speed of a CPU fan depending on CPU temperature (stepwise increase and decrease of the rotational speed proportionally to temperature fluctuations).

Onboard ports, sockets, and connectors

• Processor socket (Socket AM2, officially supports all AMD Athlon 64/X2/FX and Opteron processors for this socket)
• 4 x DDR2 SDRAM DIMM (up to 8 GB DDR2-400/533/667/800, dual-channel mode)
• 2 x PCIEx16 for video accelerators (both of them always work in x16 mode)
• 2 x PCIEx1
• 1 x PCI
• Power connectors: standard ATX 2.2 (24 pins, you can use a usual 20-pin connector), 8-pin EPS12V for a processor (you can use a standard 4-pin ATX12V connector), two 4-pin peripheral connectors for PCIE video cards
• 1 x FDD
• IDE (Parallel ATA) for two ATA133 devices — chipset-based
• 8 x SATA-II (Serial ATA II), four of them are chipset-based connectors for 4 x SATA300 devices, connected drives can form RAID 0, 1, 0+1; the other four are based on two (!) additional Silicon Image controllers (pairs of hard drives can form RAID 0 or 1)
• 3 connectors for brackets with 6 additional USB ports
• Two connectors for brackets with 2 additional FireWire ports
• 1 x CD/DVD audio connector
• AUX-In connector
• Connectors for analog audio ins and outs on the front panel
• IrDA connector
• 3 x fan headers, one of them is a 4-pin header that allows to change the rotational speed and two 3-pin headers with rpm control.

Back panel (left to right, blockwise)

Click the image to open the rear view of this motherboard

• PS/2 mouse and keyboard
• 2 x USB and 1 x FireWire
• 2 x USB and 1 x RJ-45 (Gigabit Ethernet)
• 6 x Analog Audio (Center/Sub, Rear, Surround, Line-In, Line-Out, Mic-In).

Note that the motherboard lacks COM and LPT ports on the rear panel, even its layout does not contain these connectors. That's not a peculiarity of an engineering sample, the same situation has been demonstrated for a long time by production-line Pure Innovation motherboards from Sapphire (another similarity).

Integrated Controllers

• Audio, based on the chipset support for High Definition Audio and Realtek ALC880 codec, 7.1 channel audio, front line-ins/outs and S/PDIF-In/Out jacks
• Network, based on Marvell 88E8052-NNC chip supporting 10/100/1000 Mbit/sec (PCI-E Gigabit Ethernet)
• 2 x SATA-II RAID controllers based on Silicon Image SiI3132CNU chips supporting four SATA300 devices that can form RAID 0 and 1 (in pairs)
• FireWire, based on VIA VT6306 supporting three FireWire ports.

Our attention was attracted (along with the Serial ATA demarche) by the implementation of the network controller — not linked to the chipset. Free PCI Express lanes can be used for external adapters (at least two, both of them are Gigabit Ethernet), that's it. Complete lack of built-in network support in the new southbridge alienates this ATI solution from NVIDIA. On the other hand, we may let our imagination run away and imagine an external network adapter, even richer in functions than the integrated solution from NVIDIA. However, the Marvell controller, used in the reference motherboard, offers nothing remarkable.

Settings

We used BIOS 08.00.13 dated 05.04.06. Reference motherboards from ATI traditionally offer excellent overclocking functions. A separate mention should be made of the Drive Strength option for finer (and more efficient) memory voltage control than the traditional way to raise memory voltage.

Performance

Testbed configurations:

• CPU: AMD Athlon 64 X2 4000+ (Socket AM2)
• Memory: 2 x 512 MB Corsair XMS2 PRO PC2-6400 (DDR2-800, 4-3-4-5)
• Video card: XFX GeForce 7800 GTX, 256 MB DDR
• HDD: Seagate Barracuda 7200.7 (SATA, 7200 rpm)
• Power supply unit: Chieftec GPS-400AA
• OS: Windows XP SP2

We have also published (for comparison) the results of MSI K9N SLI Platinum on nForce 570 SLI for Socket AM2.

Along with the evident similarity with the reference values, the results were notable for interesting unanimity of test tasks: the difference was always 2 units (that is seconds in archivers and MPEG encoders, fps in games).

We have also tested performance of USB and Serial ATA controllers. As is well known, their abnormally (compared to other chipsets) low performance was one of the major gripes with the previous SB450 southbridge. Good news: according to HD Tech 3.01, read/write rates are absolutely identical in both motherboards (to within 0.1 MB/s). It's quite clear that capacities of modern SATA controllers exceed requirements of hard drives (they provide excessive bandwidth).

In order to detect USB 2.0 peculiarities, we had to find a worthy challenger for this bus bandwidth. Flash drives, card readers, and 1.8" micro hard drive in an MP3 player demonstrate the write (and read) rate below 18 MB/s, which is not a limit even for the previous controller. Reading a gigabyte file from a full-sized external hard drive (similar to the one in our testbed) raised this value to 33—34 MB/s in both motherboards. The situation with writing is a tad more interesting: NVIDIA's USB controller demonstrates a tad higher performance, while ATI is slower by the same 1.5 MB/s from the reading results. But this spread is hardly significant.

Summing it all up, we can say only one thing: if you choose chipsets for maximum performance, the updated southbridge from ATI will force you to adopt other criteria. As it's very difficult to detect any differences even in synthetic conditions.

Bottom line

ATI's offer for Socket AM2 will certainly find its customers. First of all, among those who are planning on assembling a gaming PC with CrossFire support. The main objective of launching SB600 is to eliminate drawbacks in peripheral interfaces and raise functionality to the necessary level for a modern motherboard — this objective has been fully completed.

However, ATI version is still noticeably outscored by NVIDIA in the number of "attractive" options. That's why it will be interesting to those who want to assemble a computer with custom functionality and don't want to overpay for extra options. Even if the cost of competing solutions will be on the same level, ATI will still have a small advantage of a less hot chipset.

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