Macbook Air 2015 doesn't show external HDD at boot

[Koudspeel]

Hi all,

What I'm trying to do is running Windows 10 from my external HDD via USB on my Macbook Air 13" 2015. I followed the following tutorial to install Windows 10 on an external harddrive:

The thing is.. the external HDD with Windows 10 on it does get recognised by my iMac 27" late 2012 and gets also recognised by my Macbook Air 13" 2012 at bootup (hold down alt while booting). But my Macbook Air 13" 2015 doesn't show the external HDD at bootup (hold down alt while booting). So I came to the conclusion that the HDD or the installation itself isn't faulty but that something is wrong with the Macbook Air 13" 2015.

I tried to reset the PRAM by using alt + cmd + P + R, this didn't work. I installed the latests updates (am running 10.10.5 now) and it still doesn't work.

Does anyone know what's wrong with my Macbook Air 13" 2015?

Thanks in advance

 

[nebo1ss]

Many disc drives with power provided by the computer have a problem with not enough power and do no show up. The solution is a y cable that connects to 2 usb ports on the computer or failing that connect one end of the y to a usb power source.

 

[Gav2k]

Or a powered USB hub

 

[motrek]

Many disc drives with power provided by the computer have a problem with not enough power and do no show up. The solution is a y cable that connects to 2 usb ports on the computer or failing that connect one end of the y to a usb power source.

If the drive works on a 2012 MBA then it seems like it would get enough power on a 2015 MBA?

 

[Gav2k]

If the drive works on a 2012 MBA then it seems like it would get enough power on a 2015 MBA?

Not if they have turned up the over voltage protection due to a previous issue

 

[Koudspeel]

So you guys think that the HDD doesn't get enough power via USB. I'll try using a powered hub.
Is it also possible that this is firmware related? I couldn't find a newer firmware version though

 

[Gav2k]

So you guys think that the HDD doesn't get enough power via USB. I'll try using a powered hub.
Is it also possible that this is firmware related? I couldn't find a newer firmware version though

Yeah that's what I think. I had a wd 2.5" drive that did it. Would see it booting but once the OS was up I could plug it in then I noticed in system profiler it was drawing more than usual. Powered USB hub solved it as I had one sitting round but for portability I brought a USB loop back cable