Hitachi HDS72252 5VLAT80 drives (Ultra/100) on Promise Ultra133 TX2 controller

I have a small Pentium II server here which has a Promise Ultra133 TX2
controller with 2 Hitachi HDS72252 5VLAT80 drives (2 x 250 GB)
connected to one channel and one Maxtor 6 Y200P0 (200 GB) to the other
channel.

The Hitachi drives are Ultra/100 drives, the Maxtor is Ultra/133. All
jumpers are double-checked and correct.

The drives work, but the Hitachi drives seem to make strange resetting
noise. It's NOT a ticking sound, but it sounds like the heads are
moved back to an initial position at random intervals. It sounds like
a soft reset of the drive. The drives continues to work normally, but
I don't think this is normal.

In the meantime I also have the following warning in the event viewer:

The driver has detected that device \Device\Scsi\Ultra1 has old or
out-of-date firmware. Reduced performance may result.

I'm not too concerned about this, as I think it is caused by the fact
that the drives are Ultra/100 and the controller Ultra/133. But
probably related to the noise the drives make. Is the controller
issuing commands to the drives which the drives don't understand
causing them to reset??

Can the Promise controller be forced to work in Ultra/100 mode on one
channel?

Any help would be appreciated...

Grtz,
Marco