Using SSD for primary drive and RAID for secondary

Yep it will will work and your thinking is right on. You will lose the data on array when you do this so make a good backup.

It is always best when installing a SSD to do a Clean install as window will recognize the drive as an SSD and setup the system to mange it properly.

You cant operate the onboard ICH as Raid and stand alone at the same time.  Tis either one or the other but NOT BOTH at the same time.  You could add a Raid Controller as secondary storage but you cannot do as you are indicating.

Speedstep;

I beg to differ:  The ICH as used in Dell machines typically handle only two drives in RAID configuration.  If a third is added it will be a stand-alone drive.  This works fine in my XPS 9000; I see no reason it should not work on other Dell models.

Booting from drive3  does not seem to be standard in bios on the 8300 I own.

Furthermore using more than 2 ports shows up the ugly chipset issue.

On Jan. 31, Intel announced a Stop Ship on its Sandy Bridge (new Core i-series) chipset.  According to Intel, ports within the chipsets may degrade over time, potentially impacting the performance or functionality of SATA-linked devices such as hard disk drives and DVD drives.

What currently shipping Dell products are impacted?
Effective immediately, we will remove those currently shipping Sandy Bridge platforms from our websites:
* XPS 8300 desktop
* Vostro 460 desktop
* Alienware Aurora-R3 desktop
* Alienware M17x-R3 notebook             
We will have more information next week on when these products will become available again.

There are no additional shipping XPS, Vostro, Alienware, Inspiron, Precision, Latitude, OptiPlex, PowerEdge or PowerVault products impacted by this announcement.

When will we have information for customers who have already purchased one of the impacted platforms?
* For customers who have placed their order and the order has not yet shipped, these orders are on hold and the customer will not be charged. Dell will notify these customers and determine if the customer wants the order cancelled or wish to keep the order open to be fulfilled when new production material is available
* For customers whose order has shipped but not yet arrived, these customers can refuse receipt of the shipment and it will be returned to Dell. These customers will be contacted to determine if they prefer a full refund or wish to keep the order open to be fulfilled when new production material is available
* For customers whose order has been received, we are offering two options: 
1. Customers can contact Dell within the applicable return period and arrange for a full refund and return shipment of the product 
2. Customers may continue using their systems. Once new production material is available from Intel, we will be working with customers to determine the replacement steps for their motherboards if they choose to keep their system

For any customer that has experienced a service event on their system, the two points above still apply.

When will new inventory be available that does not contain this issue? Intel expects to begin initial deliveries of the updated chipsets in late February and expects full volume recovery in April.

True; I know of no Dell BIOS that will automatically look for boot code on a hard drive attached to any port other than SATA 0.  The RAID drives, however, are not constrained to certain ports.  Placing the RAID drives on SATA 2 and SATA 3, for example, leaves SATA 0 clear for a third drive which can then be used to boot the system.