Great question and actually the same debate I went through when building my home media server, although I'm only running 7xHDD, 1DVD and 1 Bluray.

Best bet is to use a RAID controller operating on a faster slot as the PCIEx1 would provide only marginal gains and likely wouldn't justify the cost. If you can find a x16 version with only 2 ports, put it in your second PCIEx16 slot and use this controller for the OS. You will see some gains on the OS drive this way.

In either instance you would save a small amount of overhead by reducing the number of drives on the onboard controller as it is already limited by not keeping up to the data throughput of 3 logical drives.

I just finished writing an answer that covers this Here

Hope this helps narrow down the options for you.

Chris

Great question and actually the same debate I went through when building my home media server, although I'm only running 7xHDD, 1DVD and 1 Bluray.

Best bet is to use a RAID controller operating on a faster slot as the PCIEx1 would provide only marginal gains and likely wouldn't justify the cost. If you can find a x16 version with only 2 ports, put it in your second PCIEx16 slot and use this controller for the OS. You will see some gains on the OS drive this way.

In either instance you would save a small amount of overhead by reducing the number of drives on the onboard controller as it is already limited by not keeping up to the data throughput of 3 logical drives.

I just finished writing an answer that covers this Here

Hope this helps narrow down the options for you.

Chris