Won't boot with USB 2.0 card

[larrymoencurly]

Why would a USB 2.0 card based on the VIA VT6202 chip not work in a VIA-based VA-503+ mobo (VIA MVP3 chipset) but work in a slightly older mobo from the same manfacturer and based on a slightly older VIA VP2 chipset? Every other USB card I've tried (Opti, Lucent, both USB 1.1, Maxtor/NEC USB 2.0) worked fine with both mobos.

With the VIA USB 2.0 card plugged in, the screen stays blank, and the mobo can't be reset from the keyboard. When I remove the card the mobo runs fine, and apparently the USB card isn't damaged. I've tried removing all the other PCI cards and plugging the USB card into each PCI slot. I've also tried changing the BIOS settings for PCI, PNP, IRQs, and configuration reset. Nothing improved matters.

The Soyo/VIA USB 2.0 card is advertised as "2.5V power supply with 5V tolerant inputs, " and I measured 2.5V on its voltage regulator chip. Does this have anything to do with my problem?
I couldn't measure 2.5V anywhere on the Maxtor/NEC USB 2.0 card.

[DrZaius]

Hi larrymoencurly,

Have you tried disabling the onboard USB first in the BIOS? It may be a conflict.

[larrymoencurly]

Yes, and I even tried disabling the COM and parallel ports and flashing to both the latest official BIOS and the original one that came with the mobo. No difference in any case.

What gets me is that this VIA USB 2.0 card works in an older mobo made from the same company and with a chipset from the same manufacturer.

Does this issue have something to do with the different power supply voltages used by PCI? The card has one notch in it, if that matters.