First post, by kanecvr
Hi guys. I want to introduce this forum to a lovely little motherboad that can run most 90's 5x86 (pentium class) cpus, and downclock most chips to 10.66MHz for XT level performance.
Meet the Lucky Star 5V-1A:
Features and sepecifications:
- Socket 7 CPU's supporting anything from a pentium 75 up to a K6-II/III at 570MHz*
- PS/2 mouse port
- USB 1.0
- 4x PCI slots
- 3x ISA slots
Chipset: VIA VPX + Via 586B southbridge (no ATA bug)
FSB speeds: 8*, 50, 55, 60, 66, 75, 85, 95* (* means undocumented)
Core voltage: form 2.0 to 3.53 V in 0.1V incerements, single or dual voltage CPU
RAM: 2x 72 pin SIMM slots witch take FPM or EDO + 2x SDRAM slots witch take modules up to 256MB in size
L2 Cache: 256kb or 512kb
Maximum memory: 512MB (2x256MB double sided SDRAM)
What makes this board special? The undocumented jumper setting for 8MHz front side bus. With this you can run a pentium CPU at 10.66Mhz with the PCI bus at 4MHz yearling XT levels of performance on a machine cabable of running a K6-II 400 @ 6x66Mhz and faster. At it's fastest documented jumper setting, FSB 75, the board can run a K6-II at 450Mhz (75x6) and maintain the PCI bus fequency at 32MHz, pretty close to the 33Mhz default. At 83MHz PCI is overclocked slightly to ~35.6Mhz witch most PCI cards should have no problem with due to an odd PCI bus multiplier setting of 2.33X witch is enabled when selecting 75 and 85MHz FSB. At 95Mhz (for those lucky enough to have this clock setting stable, since that entails a pretty big overclock to the chipset and L2 cache) you can run a K6-II CPU at 570MHz. My board is not entirely stable at 95MHz FSB - for that I need to disable on motherboard L2 cache, but that's not an issue when using CPUs with on die L2 cache like the K6-II+/K6-III.
I've compiled a document with extended jumper settings from various sources and personal experimentation as well as PS/2 port pin-out and more:
Also, here is the latest BIOS version (J3-006) witch allow for larger disk drives and allows the board to correctly identify and use SD-RAM modules:
And stock bios witch came with my board:
Before attempting to flash BIOS, please note that this board usually comes with a one-time flashable Amtel EPROM chip - witch means you will need another 5V 128kb EEPROM to update bios.