I have the same problem after having my h/d upgraded.
The delay on my system is 10 seconds before the boot process starts.
My motherboard is a PC Chips M851LU and I have the same processor.
I explored the avenues you have(Except for checking the jumpers, that's beyond me at the moment), I even rang Maxtor in Ireland to see if they could help as I assumed it was a problem with my h/d, but they couldn't help me.
Sorry I can't offer any advice, it's something I've just had to live with :-(
It seems too much of a coincidence though that we have the same brand of m/b.
Hope someone else has any suggestions for you, dagwoood.