HDD transfer rate decrease with USB devices connected

[wing0]

I've been searching up the culprit to this problem for a while.

Currently, I have a Athlon XP 2000+ system(I know it's old...but meh...no job)
with KT266A chipset motherboard that has USB2.0

HDD: Maxtor DiamondMax 9 80GB ATA133

The hdd itself is running fine, getting around 45MB/s transfer rate and is set to UDMA6 mode(133). Tested with hdtune

Problem occurs when I have an usb external hdd or usb memory drive connected to the system. My transfer rate will drop to around 16-17MB/s, once I unplug the usb device, it goes back to normal.

I'm using the usb2.0 driver from XP SP2 right now and just don't know what's going on. I have also tried two version of VIA 4-in-1 drivers, one is legacy but optimized for older generation NB, and the newest one. Both exhibits the same problem.

Searching online doesn't really reveal anything...and also this dosen't happen to my other computer which is a P4+865PE with the same hdd.

Can somebody please let me know what I'm missing here.

[shaihulud]

This could be something intrinsic to the system and may need a BIOS update or may need a toggle of a few options in the BIOS. I would make sure that ACPI is enabled, and an option PCI Delayed Transaction is too. Many motherboards do not have this enabled automatically and seem to think it should be a valid toggle. There could be a couple more but I do not know what your motherboard is.

The latest 4-in-1 driver will basically be fine. I would disregard their message concerning which chipset because there is not much of a difference with the drivers anyways. There are some caveats though. Although, they finally did get the PATA driver released and correct, and this actually could be a part of your problem too (or the problem). It will look Intel’sh if installed, something like VIA PATA – 0123. I cannot remember the name specifically, but similar. Look for the number sequence at the end of the device. A roll back of the driver should be all that is needed, and may resolve your problem.

[wing0]

This MSI board is probably the last generation of KT266A and there is only one BIOS available for it.....which I have installed.

Also I have already set PCI Delayed Transaction on. While rolling back driver sounds good, it just rolls back to the SP2 driver. Nothing new.
I've also tried VIA's usb 2.0 driver and their IDE driver....with no help...

I'm just wondering how can USB take that much resource out of the PCI bus...

[shaihulud]

It doesn’t. However, VIA is renowned for being the worst core logic company of the world. This is one chipset company I will talk bad about. This seems as if it is something intrinsic to the system or chipset then. Sorry, wish I could help more than my rant.