Overclocking
For our overclocking tests, we swapped our low-latency OCZ PC3200 memory out of the Fatal1ty AN8 in favor of some of the OCZ's PC4400 sticks, which are rated for higher clock speeds at more relaxed latencies. PC4400 memory is designed to operate at speeds of up to 550MHz, so it shouldn't bottleneck our overclocking efforts. However, running the PC4400 memory at more relaxed 2.5-3-3-8 timings could result in lower overall performance if we can't crank the clock speed high enough to compensate.

In testing, we were able to get the Fatal1ty AN8 stable with a 270MHz HT link speed, 8.5x CPU multiplier, and 3x HyperTransport multiplier. That put our DIMMs just shy of their advertised 275MHz (550MHz DDR) limits. That's further than we've been able to push any other Athlon 64 motherboard.

Despite the fact that its CPU is running less than 5% above its stock speed, our overclocked system yields noticeably better performance in both Unreal Tournament 2004 and Sphinx. The board is actually capable of much higher HT link speeds, though.

Not satisfied by 270MHz HT, we started dropping the memory clock to see just how high the HyperTransport link would go. With a 2x HyperTransport multiplier, 6x CPU multiplier, and the board's DDR266 memory clock setting, we were able to get the Fatal1ty AN8 stable with HT link speeds as high as 360MHz.

At that speed, the DDR266 BIOS setting yielded a 240MHz (480MHz DDR) memory clock, which was well with our PC4400 DIMMs' comfort zone. Because it was running a slower memory clock, the board's performance was actually lower with these settings. However, our results suggest that the Fatal1ty AN8 has plenty of HT headroom for those with DIMMs capable of greater than PC4400 speeds. Of course, as always with overclocking, your mileage may vary.

Much ado about OTES?
During testing, we noticed that the Fatal1ty AN8's OTES exhaust fans never actually spun up, even after hours of heavy loads. It turns out that with their default FanEQ settings, the OTES fans don't start spinning until the system temperature creeps above 40C.

Since we do the bulk of our benchmarking on an open test bed, we popped the Fatal1ty AN8 into an Antec SX830 case to see what kind of impact OTES might have in a typical system. We assembled the system with all the components from our open test bed system and added an 80mm case exhaust fan for good measure. Putting the Fatal1ty AN8 in a case didn't make much of a difference, though. Even after several hours of Folding@home and a looping 3DMark05 demo, the system temperature wasn't high enough to activate the OTES exhaust fans.

As far as Abit's FanEQ defaults are concerned, our system didn't need any help from OTES. Overclocked systems running extremely high voltages in small enclosures may need the extra exhaust assist, but how loud would those extra fans be? To find out, we measured the Fatal1ty AN8 system's noise levels inside the Antec case. We tested with the OTES exhaust and RAMFlow fans on at full tilt. We also measured fan noise with the fans running at FanEQ defaults and with the fans completely turned off. All measurements were taken after 20 minutes of a combination Folding@home and 3DMark05 load.

When running all out, OTES can get loud. Really loud. Fortunately, the default FanEQ settings produce noise levels that are only marginally louder than with the OTES fans completely disabled.

Unless the system temperature is over 40C, the default FanEQ settings aren't liable to spin up the OTES exhaust fans at all. That doesn't make the extra coolers worthless, though. Each OTES exhaust fan is tied to a temperature-controlled three-pin header that can easily be used to power other system fans.