user91820: I understand that Bitcoin's ASICs are a highly optimized piece of equipment and, therefore, are also very specific.   
My question: are they able to do a single (or triple?) SHA-256 hash at all? And, if so, how competitively would they be with versus a GPU?

user24925: A Bitcoin mining ASIC: 

does not attempt to complete a single hash, rather fragments of two SHA256 compression rounds which is then compared to a target, the result is never returned 
can not accept arbitrary information that is not in the form of a partial SHA256 compression round

So in terms of competitiveness, a CPU can actually complete a SHA256 hash, a mining ASIC can not, which I suppose puts it ahead in this arbitrary race. 

91820: <p>I understand that Bitcoin's ASICs are a highly optimized piece of equipment and, therefore, are also very specific.   </p>

<p>My question: are they able to do a single (or triple?) SHA-256 hash at all? And, if so, how competitively would they be with versus a GPU?</p>
 24925: <p>A Bitcoin mining ASIC: </p>

<ul>
<li>does not attempt to complete a single hash, rather fragments of two SHA256 compression rounds which is then compared to a target, the result is never returned </li>
<li>can not accept arbitrary information that is not in the form of a partial SHA256 compression round</li>
</ul>

<p>So in terms of competitiveness, a CPU can actually complete a SHA256 hash, a mining ASIC can not, which I suppose puts it ahead in this arbitrary race. </p>
