I see, well, unfortunately it seems like almost any component can be causing this.
However, to rule out any software issue, I'd suggest you to re-install Windows 7 on the SSD (just make sure you unplug the HDD again, while doing this).
If the problem persists, my suggestion would be to start testing each component one by one. Since you've already replaced the HDD and you keep getting the BSOD, we should start looking for root of the issue somewhere else. I'd recommend to start by running memtest on the RAM. Here's a tutorial that might help you with that:
http://www.tomshardware.co.uk/faq/id-1906201/test-memory-memtest.html
If everything is okay with it, then you might as well try to troubleshoot by testing the GPU:
http://www.tomshardware.co.uk/answers/id-2189736/test-graphic-card-working-fine.html
If that doesn't help, I'd suggest you to go to a professional computer repair services to test the power supply in the computer.
Keep me posted though!
SuperSoph_WD