when visiontek went out of business, their assets and name were bought by a company in connecticut if i remember . or maine, vermont something.
the assets were sold off, and the name was used to start the new company that is visiontek now. thats why they do not use nvidia now, and are an ATI house.
the people who used to run visiontek still had contacts in retail, etc. so some of them started bfg. chaintech obviously does not have contacts at say bestbuy or compusa. anyhow, chaintech is a subcontractor, and bfg is just a brand name that has connections with retail stores.