In the article, I will describe how I installed dual disk drives in an Alienware X51 desktop PC. This is actually part 2 of the process. See "HIDI#1 - Alienware X51 SSD Installation" for the first part.

Note: How I Did It (HIDI) describes the process by which I performed this task and is not intended as a general purpose tutorial for PC modifications. Simply put, this is my experience and your experience may or will vary based on your configuration and requirements.

Parts used:
StarTech.com 8" SATA Cable model number SATA8
StarTech.com 6" LP4 to LP4 / SATA Power Y Cable model number PY01LP4SATA
Quan one (1) Seagate Momentus XT 500 GB 2.5 Inch Solid State Hybrid Drive ST95005620AS

In HIDI #1, a bay converter was installed that has the capacity of two 2.5" drives and a SSD was installed as part of that process. Now the second drive will be added, a hybrid HDD.

Even with the dual drive bay converted installed, there are some complications.

While the Alienware X51 includes a spare SATA data port (three ports total on the motherboard, two in use in the factory configuration), there is no provided power for a third SATA drive.

There are two possible locations to tap for power; a Molex 4 pin power connector on the motherboard that is used to power both the existing drives and the existing SATA power cable for the HDD. Alter purchasing several power adapters and splitters, using the motherboard Molex 4 pin power connector seemed to be the cleanest and most straightforward approach. The StarTech.com LP4 to LP4 / SATA Power Y Cable model number PY01LP4SATA acts like a "tap" to in the existing power cable providing a an additional SATA power cable.

There is not much room for routing and dressing cables so additional time and care is required to insure the system can be reassembled and to minimize any impact on air flow.
Once all the parts have been obtained and the steps in HID1#1 are complete, installation of the second drive in the Alienware X51 is somewhat straight forward.

The installation of the second drives begins with:
1) Disabled the system per HIDI#1 and remove the drive cage.
2) Install the HDD in the bay converter in the available position and orientate the drive the same as the SSD.
3) Connect one end of the new SATA data cable to the available SATA port on the motherboard and the other end to the HDD.
4) Remove the Molex 4 pin power connector on the mother and connect the StarTech.com 6" LP4 to LP4 / SATA Power Y Cable to the mother board and to the Molex cable that was just removed.
5) Connect the SATA Power from the StarTech.com cable to the HDD.
6) Take the time to route all cables cleanly around the various parts.
7) Reassemble the system.
8) Power-up the system and configure the new HDD.

Here's a picture of the installed and connected SSD (video card removed to expose the drives and DVD drive relocated to expose power connector):

http://www.flickr.com/photos/jimmologist/6963232207

And there are a few follow-up notes:
1) The combine power requirements of both the Intel SSD and the Seagate hybrid HDD are less than the factory installed 1TB Seagate drive. So this dual-drive configuration should actually have less power demands.
2) Time and care is required in routing and dressing the newly installed cables (power and data). There is very little clearance in the Alienware X51 so take the time to dress the cables.

Up next: HIDI#3 - Alienware X51 NVIDIA GeForce GTX 560 Ti Installation

Here's HIDI#3 - Alienware X51 NVIDIA GeForce GTX 560 Ti Installation:
http://www.alienwarearena.com/forums/topic/13179/?comment=339990

I followed your guide and my installation was smooth and trouble free

my parts:
8" SATA Cable (both ends straight)
8" LP4 to LP4 / SATA Power Y Cable
1 Seagate Momentus XT 750 GB 2.5 Inch Solid State Hybrid Drive

The drive mount I used is a
A-RAM 3.5" to 2.5" SSD HDD Bay Drives Converter SSD-BRACKET2, it fits perfectly on the dell drive mount and gives plenty of clearance for cables between the fan and back of the drives

I was less fancy with my ssd placement, double sided pads and the optical drive case. Fits nicely.

ok, I have to ask ... why a hybrid drive for the second HDD?
It makes no sense.

You already have the SSD for your OS and thats the smart call. Thing is that the hybrids try to combine the speed of SSD and size of HDD which means that they are almost as good as SSD for booting up.

HOWEVER! They are not yet as fast as SSDs and in some cases regular HDD get really close to them ( http://www.hardwaresecrets.com/article/Seagate-Momentus-XT-750-GB-Hybrid-HDD-Review/1474/1 ).

Additional flaw of the hybrids is that they spin down more often then regular HDDs and that in turn means more ware and tear.

So for the second, data storage disk, I am not sure if the hybrid was a right call.

what about dual ssd?

Hi guys I am waiting for my x51 should be here friday but i was wondering if someone could please post a link or a list of everything i will need for this installation. From Newegg possiably and thank you in advance

Kharn888 said: I was less fancy with my ssd placement, double sided pads and the optical drive case. Fits nicely.

Man, how did u solve the power problem? How did you power the SSD? Can you please share a link with the correct cable?
Thanks