The only mobo I have seen with on-board SSD comes from gigabyte:
http://www.newegg.com/Product/Product.aspx?Item=N82E16813128505&Tpk=gigabyte%20ssd
Here is a good article about caching with benchmarks:
http://www.tomshardware.com/reviews/z68-express-lucidlogix-virtu-ssd-caching,2888.html
requirements for caching (from the article):
SSD caching, Intel-style, is constrained by a handful of requirements.
You have to be using a Core i3, Core i5, or Core i7 processor. As far as we know, caching will only be enabled on Z68 Express, so this narrows the list even further to Sandy Bridge-based LGA 1155 CPUs.
You need to have the 32- or 64-bit version of Windows Vista, 7, or Server 2008 installed.
Intel’s Desktop/Workstation/Server Express Chipset SATA RAID controller hub has to be installed and enabled (the platform controller hub needs to be in RAID mode, in other words).
The system has to be RAID-ready with the Accelerate bit enabled (presumably, Z68 will be the only platform with this switched on initially).
You need a SATA-based SSD with at least 18.6 GB of free space.
You need a hard drive present with no recovery volume.
Given those requirements, there are also a handful of limitations. First and most important, the maximum cache size is 64 GB.
Cache is only beneficial for data that is accessed multiple times. So if you open and close adobe once - no benefit. If you open and close adobe 20 times before restarting or shutting down the comp - you will see increase load times on the 2nd try of opening adobe.
With that logic, there is pretty much no benefit in boot up time. Or for first time loading of game levels.