How to fix game in BlueStacks which is displaying graphics in black

My approach, in light of the plethora of information contained in the spec of any graphics card, is to go by benchmarks. Specifically, Tom's hardware's benchmarks.

Of course, benchmarks should always to be taken with a grain of salt, since the benchmark rig might (and usually does) overpower your own in many aspects. However, I do believe that this is a good way to get a look at the "raw power" you can expect to get out of any specific card.

Tom's hardware also publish periodic recommendations to help you find the best card for your budget.

One final note: You should always check which DirectX technology your card supports (DirectX 10 being a requirement on some newer games, though almost any card on the market should support it).

I apologize for the link bombardment, but this is a really broad subject and there's always research to be done before buying a card.

It is hard to answer this question generically. Display "Mode Persistence", as it is called in the biz, is a notoriously fickle and config dependent feature. Key factors to consider:

1. Display mode (Clone, or Extended Desktop)
2. Graphics adapter (nVidia, ATI, etc)
3. Version of Windows (generally pre-Win 7 or post-Win 7)

Display modes are handled differently for these different configs. I'd also suspect that the FPS hit for running in these different configs varies.

All that said, if you want an easy way to turn off your second (or third/fourth etc) displays, most modern graphics cards provide it. Look for a "hotkey" menu in the graphics adapter GUI. For example in Catalyst:

Here you can set keystrokes for various display mode switching. I believe you'd be looking for "Disable all non-Primary displays". There many other hotkey-able capabilities you may also find useful, if you are switching between gaming and "regular" computer use.