BlueSmoke - Review : DFI AK76-SN

		Date	: Jan 22nd, 2002
		Category	: Motherboards
		Manufacturer	: DFI
		Author	: Jin-Wei Tioh

DDR has become the memory platform of choice for both the Pentium IV and Duron/Athlon, representing a changing of the guard from SDRAM. A few months back, AMD introduced the world's first Socket-A DDR platform - the AMD760, introduced to bring DDR-SDRAM to the Athlon processor and continue to do so until a third party chipset manufacturer supplies a viable DDR solution. AMD took similar steps with the AMD750 chipset while introducing the Athlon processors to the world. However, the transition this time didn't occur as smoothly or as quickly as planned, hence the profusion of AMD760-based motherboards. With greater overall performance than the VIA KT266, this chipset is still desired by many.

One manufacturer to offer a AMD760-based solution is DFI, with the AK76-SN. More accurately, we should say AMD761-based. Due to the AMD761 North Bridge being linked to the AMD766 South Bridge via the PCI bus, all manufacturers (including DFI) opted to use the VIA 686B South Bridge due to its lower price. While many would consider this practice to be taboo, there are only 2 incompatibilities as identified by AMD; the inability to support the South Bridge's IOAPIC; potential data corruption when switching into the ACPI S3 power management state (Suspend to RAM) in systems that use registered DDR DIMMs. The first is easily alleviated by adding a pull-up resistor, but there is no solution for the second.

That said, let's get acquainted with the AK76-SN :

The highlight of the AK76-SN is simply how ordinary it is - the traditional brown PCB color, the lack of integrated audio (or any OEM-ish features for that matter). Its dimensions are a humbler 12" x 8.7" (HxW), which makes this an easy fit into any case. Component placement is good but not perfect. The ATX power supply header sits close to the right edge of the motherboard, behind the CPU socket. The significance? The power supply cables would potentially hang above the CPU, thereby obstructing airflow to the heatsink/fan unit. This is one of the most common mistakes that have been committed by many manufacturers. It would definitely be better if DFI had followed the layout the AOpen AK77 Plus by placing the ATX power header next to the DIMM slots.

The DIMM slots are postion towards the far left of the motherboard, a good call on DFI's part due to the slots being less than a quarter inch above the AGP slot. Thus, DIMM installation becomes a non-issue with most AGP cards in the market, barring the Voodoo5, a full-length device.

DFI decided to integrate only 2 USB ports, including an additional header (but not the necessary bracket) to provide another 2 USB ports. The second USB header is placed toward the bottom of the motherboard, parallel to the PCI slots, an ideal arrangement for case modders and those with cases having lower-front USB ports, such as the SkyHawk aluminum line. As done on most motherboards, the front panel connectors are placed in the lower-left corner of the motherboard, ensuring that the cables do not get in the way of any expansion slots.

The IDE and floppy connectors are mounted in between and parallel to the PCI slots. While being a little further from the storage devices that we'd like, it is still a very acceptable arrangement. Every single slot on the AK76-SN is able to accommodate a full-length card, a commendable layout achievement on DFI's part.

The only other fault in the AK76-SN's layout is capacitor placement. The 6 3300uF units could definitely have been shifted about half an inch away from the CPU socket, since they currently get in the way of larger heatsinks such as the Swiftech MC462A. To DFI's credit, they did follow the "no mount zone" specified by AMD, allowing enabling the usage of heatsink/fan units which use the 4-lug mounting system, such as the Zalman CNPS5000 and the aft-forementioned Swiftech MC462A.

The AMD761 North Bridge, the core of the AMD760 chipset, sits between the CPU socket and the AGP slot, roughly an inch from each. It provides all the major features of the chipset, namely DDR, 100/133MHz FSB as well as AGP 2x/4x support. While this chipset is now bowing out of the market (being replaced by both the nForce and KT266A), nevertheless, it is still a solid part providing excellent performance. DFI chose to implement an active chipset cooling solution. It looks generic, but it gets the job done.

The motherboard sports 2 DIMM slots, capable of accommodating up to 2GB of DDR-SDRAM. In reality however, the currently largest available DDR DIMMs are only 512MB in size, thus effectively limiting main system memory to 1GB.

Earlier, we classified the AK-76SN as an AMD760-based board. More accurately, we should have said AMD761-based. Due to the AMD761 North Bridge being linked to the AMD766 South Bridge via the PCI bus, all manufacturers (including DFI) opted to use the VIA 686B South Bridge due to its lower price. While many would consider this practice to be taboo, there are only 2 incompatibilities as identified by AMD; the inability to support the South Bridge's IOAPIC; potential data corruption when switching into the ACPI S3 power management state (Suspend to RAM) in systems that use registered DDR DIMMs. The first is easily alleviated by adding a pull-up resistor, but there is no solution for the second. For expansion slots, DFI adopts a more power-user oriented 1/6/0/0 (AGP/PCI/ISA/AMR) configuration. As mentioned earlier, all the slots are capable of accommodating full-length cards.

DFI chose to endow the AK76-SN with a lower number of capacitors, but with each capacitor being a large 3300uF unit. All good and well, as the CPU should receive sufficient and steady power. In the overclocking department, the AK76-SN features a jumper for FSB range selection (ie. either 100-132MHz, or >= 133MHz), adjustable in 1MHz increments via the BIOS. The FSB clock generator used is capable being ramped up to 166MHz. CPU core voltage (from 1.475V to 1.85V) and multiplier selection are done via DIP switches. However, VIO and DIMM voltage adjustments are absent.

Surprisingly, DFI bucks the current trend by forgoing some form of integrated audio. Power users might welcome this, since they usually go after higher-end hardware-base audio solutions (eg. the SBLive!). Moreover, the exclusion of audio functionality helps to lower the cost of the board by taking up less silicon real estate.

The garnishings of this bundle are minimal, with DFI including a product manual, driver CD, quick reference sheet, floppy and 80-pin IDE cables, just the required essentials for more seasoned end-users to get started.

We'll let the AK76-SN prove its worth...

For the results below, the AK76-SN was run with standard parameters (ie. no overclocking) at 800MHz (6 x 133 FSB), CAS 2. Please note however, that you shouldn't compare the results obtained here to rate a Socket-370 motherboard and vice versa.

We would like to take a moment to thank the sponsors that have made this review possible. The Thermoengine was supplied by ThermoSonic Technology, the Artic Silver II TIM by Arctic Silver LLC, and the Siluro MX400 by ABIT.

In addition to tests using standard parameters, we performed overclocking tests to ascertain the highest FSB speeds the system could sustain. We started by setting the CPU (a pencil-unlocked Duron 800) to run at 133MHz FSB with a multiplier of 6 (for a speed of 800MHz) and verified its stability via informal testing using Ultra-X's RAM Stress Test, Stability Test and HotCPU. The FSB was gradually increased the tests repeated. All tests were done BIOS default memory settings with the CAS latency set to 2.5, to minimize the chances that the RAM was the limiting factor. Ultra-X makes some of the best professional PC diagnostic tools on the market, and quite a number of people use them on a regular basis including some of our acquaintances. Their RAM Stress Test has proven quite effective in ferreting out any memory instability problems, which is one of the things that is evaluated when increasing the motherboard's FSB.

We managed to ramp up the FSB to 146MHz, a 10% FSB overclock with the processor running at 803MHz (5.5 x 146). Stepping even 1MHz beyond that resulted in drastic instability, with none of our benchmarks being able to be completed successfully. Though this is certainly an above average figure for AMD760 motherboards, we can only speculate how much farther the AK76-SN will go if VIO and DIMM voltage adjustments were present.

The good :

• Active chipset cooling solution. Although generic looking, the supplied chipset HSF gets the job done well.

• Good stability under both standard and overclocked (146MHz FSB) conditions.

• Good layout, save for the slightly close 3300uF capacitors. All expansion slots are capable of accommodating full-length cards, IDE, and floppy headers are placed to minimize cable clutter and maximize airflow to CPU.

• Observes AMD "no mount" zone, with support for heatsink/fan units such as the Zalman CNPS5000 and Swiftech MC462-A.

• No extraneous OEM features such as AMR slots or integrated audio, as well as a perfect expansion slot configuration of 1/6/0/1 (AGP/PCI/ISA/AMR).

...and unfortunately the bad :

• Ho hum aesthetics, with the standard brown PCB and black North Bridge heatsink.

• No memory interleaving options in the BIOS. The lack of interleaving hurts memory bandwidth scores.

• Overclocking is inconvenient, as you have to manually set the CPU multiplier and core voltage via DIP switches. Although FSB speed is adjustable in the BIOS, you still have to set a jumper to select the FSB range. Lack of VIO and DIMM voltage adjustments, which could have limited the AK76-SN's overclockability.

• The bundle is not as user-friendly as it could be, lacking additional software and some form of quick start guide.

So how does the AK76-SN weigh in? Excellent stability up to a 146MHz FSB, no crashes in our rigorous FreeBSD makeworld tests, coupled with the competitive performance expected from the AMD760 chipset. The 1/6/0/1 (AGP/PCI/ISA/AMR) expansion configuration and lack of integrated features is a boon to the power user. DFI also put the time into component layout, generally reducing cable clutter, allowing all slots of accommodating full-length expansion cards, and even observing AMD's no mount zone to allow the use of larger heatsinks such as the Swiftech MC462-A. Unfortunately, there are a few shortcomings to the AK76-SN. VIO and DIMM voltage adjustments are absent, probably limiting our maximum achievable FSB to 146MHz. The use of DIP switches to control the CPU multiplier and core voltage is an inconvenience, and should have been implemented in the BIOS as with other manufacturers' solutions. While it is targeted toward power users, the AK76-SN could stand to include a few more features such as additional software and a quick start guide. Lastly, though a minor point, it could have been a little less everyday looking. If you want a solid, reliable AMD760 motherboard with minimal OEM features, the AK76-SN is right up your alley. Highly Recommended!