No LSI/AMI 1600 has four internal connectors. Two internal and four external vhdci. I have owned almost a dozen of the four channel (enterprise 1600's) and maybe fifty of the two channels (Elite 1600's) over the last four years. I know them very well.
Isnt the HP 4m actaully a HP OEM of the AMI enterprise 1600? I know the 2 channel is just the HP OEM of the Elite 1600 AMI series. I assume the 4m is just HP's OEM of the Enterprise 1600.
With those drives you do NOT need a 4ch controller. I hate the adaptecs for performance.
Grab an Elite 1600 WITH BATTERY and 128mb cache on ebay for $100 to $125 bucks.
Yes you can combine the Elite 1600 series with a regular scsi controller also no problems.
I was never real impressed with these controllers raid-5 performance. If you want redundant go raid-1. Actually with the 128mb cache just setting them up as single drives and seperating the I-O across the drives with OS on one, program, on anopther, swapspace/tempfiles on another etc.. will feel very fast.
Get a big ide drive to back to.