You are certainly aware of it, the 'ICH' = I/O controller hub of i820 and i840 (it's the same for both) is capable of 'UltraDMA66' or 'UDMA' or 'ATA66', which stands for a maximum data transfer bandwidth of 66 MB/s between the system and the IDE-hard drive, as long as the hard drive supports it. The 440BX chipset is only able to do 'ATA33' = up to 33 MB/s between system and IDE HDD.
Now which driver supports the new ATA66 under Windows98 and what do you have to use under WindowsNT even for ATA33? Intel has finally released a pretty swanky driver, which you can find here . This driver works for Windows98 as well as for WindowsNT, although the install-routine under NT has got a little bug that you will notice after installation, if you look into the 'SCSI-Devices' control tab. There you won't find the new driver, although it's running fine. Instead you'll see the old standard-IDE driver marked with 'not started'. Anyway, whoever is using IDE disks and Intel-chipsets should have a look at Intel's new Ultra ATA driver.
What should we see when testing the different chipsets against each other? Well, I would like to see superior numbers of i840, showing its impressive 3.2 GB/s memory bandwidth, which is double the bandwidth of i820 and even quadruple the one of BX. BX should look bad in 3D-applications, since it's the only one of the three without AGP4X-support. i820 should be somewhere in between i840 and BX, especially in memory-intensive applications. OK, can you agree with that?