AOpen
AOpen AP5T
This 430TX chipset board features CPU temp monitoring, 512 kB L2 Cache, 2x DIMM, 4x PS/2 sockets, 3x ISA / 4x PCI slots and outstanding quality. This boards runs stable up to 83 MHz, but strangely I had to switch the K6-233 down to 2.9 Volts (!) to run reliably at 250 MHz with the Toshiba SDRAM. The Shuttle HOT-565 has similar features but no switching voltage regulator. AOpen seems to become a reliable manufacturer for 83 MHz boards just the way ABit is doing with the AB-TX5. Both boards support Ultra DMA/2, 64 MB cacheable area (SDRAM or EDO), no ECC support. If you want to use the 233 MHz K6 processor, be aware you get rev. 3 or newer, because you will need 3.2 V support for this CPU. Revision 3.1 also has jumper settings for 2.2 Volts, which the K6 266 most likely will tolerate. The performance of the AOpen TX chipset boards is fine once again, particularly with the K6.
AT format; AT power supply; Intel 430TX; 3x ISA, 4x PCI; 4x SIMM, 2x DIMM; Award flash BIOS; 512 kB PB-Cache (6 ns); external frequencies: 60, 66, 75, 83 MHz; BF2 jumper missing, I/O chip: SMC; busmaster Ultra DMA 2 or PIO 4 onboard; FDC onboard; 2x serial 16550; 1x EPP/ECP parallel; 1x PS/2 mouse (without connector); 1x USB; IrDA support; core voltages: 3.2V, 2.9V, 2.8V, 2.2V. NCR SDMS support ver. 3.07.
AOpen AX5T
Revision 3 has some voltage selection jumpers that are probably reserved for 2.1 or 2.2 V core voltage. Thanks to the 430TX chipset it features the same limitations (64 MB cacheable, no ECC) and advantages (UDMA/2, SDRAM support). Its performance is good, as with the AP5T. Other manufacturers should take a look at some of the AOpen features, e.g. the admirable stability at 75 and 83 MHz bus speed; you can say it's more stable than fast at 83 MHz. The only comparable boards are the ABit AB-TX5 and partially the Shuttle HOT-565/569.
ATX format; ATX power supply; Intel 430TX; 4x ISA, 4x PCI; 4x SIMM, 2x DIMM; Award flash BIOS; 512 kB PB-Cache (6 ns); external frequencies: 60, 66, 75, 83 MHz; BF2 jumper equipped, I/O chip: SMC; busmaster Ultra DMA 2 or PIO 4 onboard; FDC onboard; 2x serial 16550; 1x EPP/ECP parallel; 1x PS/2 mouse; 1x USB (not on placed with the other connectors, cable missing as well); IrDA support; core voltages: 3.2V, 2.9V, 2.8V, one reserved jumper, possibly 2.2V or 2.1V. SDMS support ver. 3.07.
