L O S T C I R C U I T S

Layout

ASUS is one of the companies that strictly conforms to the AC97 standards. Unfortunately, like many standards imposed by some know-it-all-organizations some of the AC97 specs are a far cry from reality or from what would even be desirable. A case in point is the mandatory abolishment of the ISA standard / interface which has no other reason than to increase the profit margin on some add-on cards. Therefore, we are confronted with something as idiotic as an AMR slot. There is no point in blaming ASUS for this useless feature, some of the major OEM customers will not buy any piece of equipment that doesn’t conform to industry standards. On the other hand, the substitution of an AMR for an ISA slot is another perfect example of how generalized standards are often based on totally incompetent decisions. The victim is the consumer

For most users, the jumperless configuration of the A7V possible through the BIOS will suffice. In case this is the option of choice, it is necessary to enable JumperLess operation mode by bridging pins 2 and 3 of the JEN header next to the ASUS ASIC. Those preferring manual setting of the core voltage, can do so by means of a 4 x 4 pin header directly adjacent to the socket 462, covering a range from 1.075V to 1.85V. The default setting is to recognize the original VID of the CPU. The I/O voltage cannot be set within the BIOS, however, a 4 pin header between the ATX power connector and the power supply fan header allows settings of 3.35V, 3.56V and 3.69V. On top of the VID jumper block, two additional pins allow the attachment of the ASUS P2T thermal probe for monitoring of the CPU heatsink temperature. The equivalent header for monitoring of the power supply temperature is on top of the DIMM slots.

Those daring to set the FSB manually, find a four set dip switch block to the right of the DIMM with documented settings of 100, 103, 105 and 110 MHz. I mentioned earlier that there are ways of changing the multiplier settings on the Thunderbird / Duron through the mainboard. This is done by a 6-way dip switch placed flush against the FSB dip switch block (only boards without on-board sound). The settings are not mentioned in the manual but silk screened on the PCB. Here it gets really interesting since, aside from the generally accepted scheme, mostly derived from AMD’s data sheets, we found second way of changing the multiplier settings. Please keep in mind that these settings were found empirically (with a little use of brain) and conflict with AMD’s data sheets (but they still work). Please keep in mind , though, that using the settings posted here is strictly at your own risk.

Other connectors

Four fan headers (2 x CPU, 1 power supply & 1 chassis) should suffice to provide adequate cooling, even in the case of the Thunderbird with heating power reminiscent of the days of the AMD K5. Other connectors include the SMBus header for monitoring of remote devices, Wake-On-LAN, Wake-On-Modem, infrared, and, of course, the five additional USB headers. In the case of the audio on-board version, the necessary headers for direct access of the AudioCodec are included in the PC-99 specified colors for the respective device (Aux, CD, Video) and an additional voice/modem input. Moreover, ASUS has added separate headers for direct microphone-in and true headphones out. The individual components of the AudioCodec can be disabled separately or as a whole via a jumper block on the far left at the level of the third and fourth PCI slot.

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