I just finished building a Maxiumus V Extreme with an ADATA 256 GB mSata card which I bought from Newegg.
http://www.newegg.com/Product/Product.aspx?Item=N82E16820211664Three things I learned are:
1) Install the mSata card and mini PCIe onto the mother board first than mount the motherboard in the case. If you follow along with the basic install instructions, the mSata and mini PCie installation is towards the end of the basic instructions. It should have been mentioned first.
2) Because the mini PCIe has to mount along side of the I/O shield for the WIFI antenna connectors it is possible to knock the mSata card out of alignment in its socket. Carefully inspect the mSata card after you first install it than again after you mount the motherboard into the case than one more time after you are finished installing the WIFI antenna connectors.
3) My ADATA mSata card was recognized immediately upon the first boot of the Maximux V Extreme. However, Windows 7 64 did not want to install to it and I was getting a hex code error message. After spending 15 minutes with the partion manager under advanced options in Windows 7 installer, I realized that I was not going to win the battle of creating and deleting a primary partion to solve the problem. But I did create a primary volume spanning the full size of the mSata card.
To solve the problem I went into the UEFI bios and I did a boot override to the mSata card. If I remember correctly, it was under advanced -> Sata -> boot options at the bottom of the page. The next reboot with the Windows 7 installation DVD, I was able to install Windows 7 directly to the mSata card.
I hope this helps everyone.