I want to install a 3rd HDD but system will not boot up

[Vincemy82]

The desktop motherboard has 5 SATA heads (of which 2 were used for the primary HDD and DvD in the original configuration) and the casing has 3 bays for HDD but there is no extra power cables from the PSU. 

I have installed a new SSD as my primary drive and designated the 1 TB HDD which came with the desktop as my secondary and the desktop works just great.

Now I tried to install another 1.5 TB HDD for storage. I used a SATA power Y-cable (1 male to 2 female) to extend the existing power cable. However to my disappointment the system can't boot up. I guess the current 300-watt PSU is inadequate to boot up 3 drives from a single power cable with extension.  

Questions:

1] does HP sell a 500-watt PSU with power cable for 3 SATA HDD? 

2] is there a compatible PSU in the market (ie. not HP) which can fit into the Envy 750-103D? Brand/model and how much?

Thank you.

[Big_Dave]

Hi,

The issue is not the power supply.

Try the following:

Unplug the original HD. Do not plug the original HD back in right now.

Download W10 from Microsoft and do a clean install on the SSD.

[Vincemy82]

I think you misunderstood my problems.

The SSD is already my bootable primary drive and the original 1TB HDD is now my secondary drive. I wanted to install a 3rd drive (1.5 TB) with a SATA power Y-cable as there is no extra SATA connector of power. However, the system can't boot up with the 3rd drive attached - system can boot up fine with the SSD & 1TB HDD. So my conclusion is the original PSU has insufficient power to boot up 3 drives.

[wb2001]

Unplug the power from the DVD drive.  You get a few extra watts, but will test your theory.

[Big_Dave · Accepted solution]

Hi,

You probably misunderstood my reply.  Unplug the original HD boot drive.

Your issue is not the PSU lacking insufficient power.  I have observed plently of HP PCs with a 300 watt PSU that would support three HDs off one SATA power cable.

Perhaps the third HD is formatted incorrectly or is faulty.  The other possibility is that your SATA Y cable connection is faulty.  You'll need both 5V and 12V.  Additionally, if you have made any other hardware modifications to your PC that you have not stated, then it's possible that you may need a bigger power supply.

[Vincemy82]

For the record I found out that my 1.5TB HDD was faulty and after replacing it with another HDD the PC powered up fine. My system now has 3 HDDs (ie. 240GB SSD, 1.0TB HDD & 1.5TB HDD) but to ensure the 300watt PSU has enough juice to power all, I unplug the power to the DvD player as suggested by wb2001.

Thank you all for your help. Cheers.