Performance : ide = scsi = ide+scsi ??????

[mucky]

Hi,
I recently installed an Adaptec 19160 scsi card and a 18Go IBM scsi drive (10000rpm), and when I did the Davec test, I still had exactly the same results than with the ATA100, that is to say 25tracks limited by the disk.
More amazing, when I split the tracks over the disks (12 on IDE and 13 on scsi), I'm still unable to get over the 25th (it's still written that the disks are limiting, not the cpu).
Isn't that odd???
I have to say that HW buffer size is 2048 and my DAE playback buffer is level 8.
I also have to mention that I'm low latency monitoring, because if I uncheck it, then PT says that it needs more cpu power, which I also don't understand at all.
my configuration :
Athlon xp 2000+ non overclocked
ASUS A7V333 MB
512Mo DDR2700 + 512 Mo DDR 2100
3 IBM ATA100 HDD
1 IBM SCSI HDD
Watercooled and racked unit

Any help greatly appreciated, thanks!

[Stone Knife]

mucky-
From what I've been able to gather from the knowledgebase, the SCSI controllers can wind up hogging the PCI bus, creates a bottleneck, and you wind up getting worse performance than if you'd just strung up a couple 100/133 drives.
Allen H. has some recommendations in his under $900 PT machine thread which include a certain model of Promise brand (IDE) controller.

A common theme in these trials and tribulations with PT host systems seems to be: what works for everything else may not necessarily be the best thing for ProTools LE.