Affinity Mask and Affinity I/O Mask
I'd consider many other options before I played with these

Some things to check here on SO: https://stackoverflow.com/a/2009693/27535

Additionally...


indexes: are your writes scanning not seeking?
key: do you have GUIDs as clustered indexes (bad idea!)
triggers: no emails being sent on INSERT or CURSORs?
disk layout: separate fast RAIDs for data and logs, per database?
autoshrink/autoclose + associated file growth
unmaintained statistics and indexes
..


Basically, your problem will be poor design poor indexing or poor hardware...