How many usable SATA III 6gb/s ports does the EVGA X79 Dark Motherboard have?
If I was migrating from an old mobo and pulled my four SATA 6gb/s  ssd's with read and write speeds of 500 and 200 mb/s, what ports would I use to get highest speeds and would I achieve 500 mb/s like I could on my old mobo?

Two. It has 4 more 6G on a Marvell controller.

I'm using my three SSDs on the Intel ports; the boot drive is on a 6 and the others are on 3. I haven't noticed the speed hit.

Were you trying to post a benchmark? You have to have a few more posts before you do. The best option in my opion if you are going to raid four SSDs would be to use the SATA 2 ports. In raid they should be very fast even on a SATA 2 port. However if you plan on using the SSDs separately then what I suggest is that you put two drives on the SATA 3 ports and the remainder on the SATA 2 ports. Another option is to raid two drives on the SATA 3 and the other two either alone or via raid on the SATA 2.
 
You can use the Marvel ports also for raid or as a separate drive connection but I tend to like the Intel native port support better.

Ok, thanks (Sorry, yes it was benchmark).
After a bit more research, it seems I will be ok with SATAII;

 
I just do not want a bottleneck, i'm still new to hardware.
I have a couple more issues to iron out, which I will post in new thread (and one day may be able to post pictures:-)
 
P.S. If anyone has any other data on video read/write speeds please let me know.
Thanks
 

punky47
I have a couple more issues to iron out, which I will post in new thread (and one day may be able to post pictures:-)
 
Thanks
 

Hang in there punky, you have to walk before you run :)
Seriously, glad I saw your thread here - I am gathering components for my new Dark build, have most of them now - and I have two of the Samsung 840 Pro 256gb SSD's, I will be sure to plug mine in to the two native Intel 6g ports.