Here's my impressions on the board now that I've had it for 6 days.
Memory - The Corsair Twinx PC3200LL (2x256 meg) would not boot @ 400 MHz at 2.5 volts, no matter what the timing was set to. I'm using OCZ PC3200EL at 400 MGz dual channel at 2,6,3,2 timing and 2.5 volts.
CPU heatsinks - I'm using the stock heatsink that came with the 3.0 GHz cpu. It has a copper inlay and was a nice design. Easy to install. Temps idle at 93 F cpu and max at 114 F full load. I've overclocked the cpu to 240 fsb (3.60 GHz) successfully (with ram @ 1.6x, or 383 MHz). On the first AOPEN AX4C-Max board (which I thought was defective but wasn't) I had mounted a Swiftec MCX4000 rev 1.0. It fit but the chipset fan power plug was in the way of the edge of the heatsink. I had to bend it sideways to get the heatsink to fit. No problem with chipset fan getting in the way of the MCX4000.
Since the stock heatsink is working so well and I do not run overclocked I decided not to put the MCX4000 on the second board.
Hard drives- I have a WD ATA100 80 GB 8 meg cache and a Maxtor ATA133 80 GB 8 meg cache drive. I've tried them on the on board ATA133 raid connector, on board Promise SATA raid connectors (with SATA to ATA adapters from OKGEAR), and on the Intel ICH5 SATA Raid connectors (with the adapters). All 3 setups worked. Performance was slightly higher on both the Promise SATA and ICH5 SATA over the parallel ATA133. CPU loading appeared to be slightly higher on the parallel ATA133 connector but not enough to be a problem. I did find one annoying problem when connected to the ICH5 SATA adapter, the drives would click very loudly several times when shutting down or rebooting the PC. Almost sounded like the drive stepper motoro was being connected/disconnected. Since I didn't want to trash the drive I moved back to the Promise SATA connectors. Sandra hard disk performance on both the Promise SATA and ICH5 SATA was just over 32000 (didn't write down exact numbers but very close to each other). I do have an email in to both AOPEN tech support and OKGEAR regarding the clicking on shutdown/reboot.
Board layout - Very nice (except chipset fan power plug too close to heatsink which may affect putting some aftermarket heatsinks on the board. There is another 3 pin fan header locaed in the bottom front corner of the board and the chipset fan power can be extended to there, then the chipset fan header could be removed or bent over (taped) to make room for a larger heatsink. As stated above I just need to bend it on a 20 degree angle to get the MCX4000 heatsink to fit. Connectors are laid out nice, especially motherboard and P4 power connectors. No longer need to have the power cables going over the memory or cpu to plug in. Using an Antec Lanboy case the motherboard fits well and cabling was routed to allow very good airflow.
Overall satisfaction - very satisfied at this time. I was one of the first to get a retail AOPEN AX4C-Max and ventured into uncharted waters (as far as setting up ICH5 SATA and the memory issues with the Corsair ram). What I perceived to be problems were not problems with the motherboard. There is still the issue with the clicking of the drive on shutdown/reboot when connected to the ICH5 SATA connector. Intel states they do not support the use of the SATA to ATA133 adapters so I do not know if those adapters are the problem or not. The Promise SATA raid works just as well as the CIH5 SATA raid so it is not a problem for me with two drives.
Here's a list of my system:
AOPEN AX4C-Max motherboard with 1.02 bios
Intel P4 3.0 GHz cpu with 800 MHz fsb
2x256 meg OCZ PC3200EL ram (dual DDR) at 2,6,3,2 timing and 2.5 volts
Maxtor ATA133 80 GB 8 meg buffer drive
WD ATA100 80 GB 8 meg buffer drive
ATI Radeon 9700 Pro using CAT 3.2 drivers
SB Audigy sound card using Audigy 2 drivers
Windows XP Pro OS with SP1
Sony DRU-500A DVD +/-rw
TDK 2440b CDrw
Toshiba 16x DVDrom
Antec Lanboy case with True Power 430 power supply (added to replace 350 watt PS)
Dave