Problem with "OS X 10.10.4 Yosemite Virtual Machine" within OS X 10.8.5 Mountain Lion

I have an iMac 27 inch, mid 2011 running on OS X Mountain Lion 10.8.5*. I am trying to set-up a virtual machine using OS X Yosemite 10.10.4 and the there is a serious video issue. The virtual machine is working BUT everything is super slow...

HINT: When I start OS X Yosemite Virtual machine, I always see a line "screening" the screen, from top to bottom, indicatiog the machine has trouble rendering the screen. For ME this is a clear indication that what I try (tried) didn't worked.

* Processor 2.7 GHz Intel Core i5
* Memory 16 GB 1333 MHz DDR3

I tried all (I think) the solutions that I found on the internet, but nothing is working...

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I tried [ sudo nvram boot-args="debug=0x10" ] in the computer itself, not working
I tried [ sudo nvram boot-args="debug=0xd4e" ] in the computer itself, not working
Nothing anormal in the "Activity monitor" window of the Yosemite virtual machine OR in my computer itself.
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Please help!

 

Hello JivRey,
Could you please tell us which version of Parallels Desktop are you using?
Also, please tell us what is the OS X of your Virtual Machine that you are trying to set up and what is the Host OS X.

 

I am using Parallels Desktop 10 (10.2.2)
Host : OS X 10.8.5 Mountain Lion
Virtual Machine : OS X 10.10.4 Yosemite

 

And now? I am not waiting for this issue to be resolved to play games. I need this working for very important work purposes. Thank you.

 

Hello,
Could you plz try to uninstall Parallels Tools and then re-install them and also make the necessary changes in you Parallels Desktop configuration settings as mentioned in this Kb: http://kb.parallels.com/112476

 

I did uninstall/re-install Parallels tools: No success
I did all the necessary adjustment regarding video configuration: No success
I did added memory and/or CPU (Multiple combinations): No success
I deactivated Mission Control (In my computer & in the virtual host): No success
I tried [ sudo nvram boot-args="debug=0x10" ]: No success
I tried [ sudo nvram boot-args="debug=0xd4e" ]: No success

 

@JivRey please try the steps below:
1. Shut your VM down and open the VM configuration
2. In the VM configurations open the Hardware tab -> Boot order
3. Paste the following flag in the Boot Flag box:
vm.efi.mac_recovery=1

Check the issue and please let us know the results.

 

And what is this suppose to change?? It just forces the Virtual OS X to show the utilities to restore the OS.. The same way I would hold ALT on startup to re-install my system.. This virtual OS X Yosemite has just been installed, it is a fresh, new installation. Sorry but unless you mention me that by re-installing the system (Which has not been mentioned), for me, this is not looking close to a solution.