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Motherboard Modifications32 bit config jumper location information.There appears to be a compatiblity issue between the Hint PCI bridge chip and the ALI southbridge chip when the ALI is on the secondary (32bit) side and the primary side is run 64 bit wide. This issue affects all versions of the motherboard fitted with the Hint bridge. Configuring the primary PCI bus to start up as 32bit instead of 64bit can considerably help reduce (or even eliminate) freezes due to sound loss. It is unclear whether there is any other solution to this issue at this time. It is being actively pursued with both Hint and ALI, the relevant chip vendors. As shipped the only device operating 64 bit to the xScale chip is the Hint/PLX bridge. Thus configuring the primary bus to be 32 bit would not appear to have any adverse effects.
The pictures below show how and where to fit a pair of jumper pins in the (unused) PL601 location to permit 32bit primary bus configuration. Connecting these 2 pins together, e.g. with a jumper, will force 32bit operation; leaving the 2 pins unconnected will re-enable 64 bit operation.
Additional optimisations:To reduce the likelyhood of noise on the reset wire affecting the reset system a 220pF capacitor is normally supplied soldered to the rear of the pcb across pins 15 and 16 of connector PL301. The 'red blob' supplied with the UDMA update shipped to all owners of machines bought before Easter 2003 contained a suitable capacitor to achieve this. I have found that it can also help to provide a 1K2 pullup resistor between pin 1 and pin 15 of this connector. Pin 1 is 3v3, pin 15 is the reset input, pin 16 is 0v.
John Ballance, Last updated Saturday the 17th of January, 2004
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