I heard somewhere that workstation cards aren't worth it.  But I don't remember why.  

I've got a workstation card (FireGL V3900) and it's mining 85ish mhashs and consuming about 50 watts (power rating from this site: http://www.sapphirepgs.com/presentation/product/product_detail.aspx?pid=48&psn=000101).  The 7750 puts out about 120 mhashs (according to this chart https://en.bitcoin.it/wiki/Mining_hardware_comparison ) for roughly 200 watts (power rating from this site: http://www.tomshardware.com/reviews/radeon-hd-7770-7750-benchmark,3135-14.html ).  

Am I doing my math wrong or is my workstation card putting out about 42% more mhashs per watt than the 7750?  I'd also like to add the V3900 hardly exceeds 60C (62C max) and my case sucks for cooling.  I compared to the 7750 because the chart shows that card for getting most mhashs for the least energy.


EDIT: OK I took a closer look at the list. ....The 7750 isn't the most mhashs per joule, but def is one of the top (according to the chart)