Here are some chipset drivers for the 800 Series (including 840) motherboards and various Operating Systems: http://downloadcenter.intel.com/Detail_Desc.aspx?agr=Y&ProdId=816&DwnldID=8178&ProductFamily=Chipsets&ProductLine=Chipset+Software&ProductProduct=Intel%c2%ae+Chipset+Software+Installation+Utility&lang=eng
Make sure you get the motherboard model number correct as Intel Server motherboards don't seem to have the model number you've given. If it's an OEM board e.g. Compaq or HP, once you've found the precise model number (perhaps from the BIOS setup screens), any BIOS updates may be on the OEMs websites (or even Intel's Website under 'Discontinued' products IFits a Retail Intel board. I don't think the product is so old that there's no hope of finding relevant drivers still, you just have to make sure you get its details correct. Time to get the magnifying glass out and check for identifying details.