You MAY not need to get exactly the same mobo. SOME of the chip makers that supply the southbridge chips on mobos have maintained compatibility of their RAID implementations from one chip model to another. To check on this, find out exactly what southbridge chip your old mobo had, and go to the manufacturer's website to look for information. Alternatively, contact Tech Support for your old failed mobo and specifically ask if they can recommend a new mobo that will handle your RAID5 disks properly.
REMEMBER that it is probably important to know exactly which HDD is plugged into which SATA port on the old mobo, and then to duplicate that arrangement on the new mobo.
I actually had to use this on a system I built. When I chose the mobo, one factor was that its southbridge chip maker guaranteed that, in its future chips, they would maintain compatibility so that newer mobos made with their chips would read RAID drives from an older mobo. A few years later it happened - the mobo failed and I was worried about the RAID1 array. I sought out a new mobo from a different manufacturer, but one that used a southbridge chip from the same supplier as on the old mobo. (I don't even think it was the same MODEL of southbridge chip - just the same manufacturer.) When I connected it all up and flipped the switch, the thing just booted and ran perfectly! The new mobo handled the old RAID1 drives just fine, as the chip maker had said.
Again, this is very UNlikely to work if you are switching mobos and designs without caution. BUT if can work if the southbridge chip maker has made it work as a policy.
How do I Recovery of Data from Raid 5 Hard drives after mother board dies
Here is what i would do - I assume the raid volume is use in Window OS
1_ First clone each individual drive with http://clonezilla.org/, so you wont mess up the original HDD
2_ Connect cloned HDD as JBOD via Port Multiplier bridge and SATA host supports PM ware
or into the new MB with enough SATA port to support the array
3_ You should be able to see these drive in Disk Manager
3_ Do not format or partition it, even OS asking, just ignore it
4_ Down load and run this software : http://www.runtime.org/raid-recovery-windows.htm
You should be able to see your data, but you wont able to save unless you buy the software.
Which is not too bad for recover the data cost.
Remember this is a tedious process, so be patient. This is why data recovery charge 100, 1000's of dollars