I guess what I am trying to say the backplane on this intel server are limited to 6gbps even in its pass through configuration. Unless I am doing something wrong, I cannot get my 12gb sas ssd to connect to 12gb sas controller at 12gbps link speed, while in a supermicro passthrough backplane I can get 12gbps link speed just fine with the same hardware.I'm not sure what you are saying. Obviously if you are using a 6Gbps backplane that will limit your disks and controllers as the connection passes through it.
My statement was to the use of an expander in these types of cases. There is a strong possibility (depending on the expander used) that you will saturate the 1 (possibly 2?) SFF-8087 links from the expander to your controller before you reach 24 SSD's.