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[Turionaltec]

Wishing to share this computer trouble-shooting knowledge somewhere, I figured this was as good a place as any.

I was loading software on someone's Dell Dimensions and I noticed data transfer seemed to be going quite slow. I check in Device manager. Strange, the hard drive was only running at UDMA mode 2 (33MB/s) when the hard drive (fairly new) and motherboard (Pentium 4 era) should be capable of Mode 4 (100MB/s) if not Mode 5 (133MB/s).

Typically the first thing to check is the cable (40 wire cables can only run UDMA mode 2, while 80 wire cables can run UDMA Mode 5), but I had personally installed the hard drive and suspected I'd have made sure there was the correct type of cable in it.

I opened the PC to double check and to take the opportunity to clean out the dust bunnies. Sure enough the hard drives were connected to a Dell factory 80 wire conductor, and set to Cable Select.

As it turned out it was a strange BIOS setting. Device type was set to:
Primary Master: Hard Drive
Primary Slave: None
Secondary Master: CD-ROM
Secondary Slave: None

Even though windows was picking up the slave devices, according to what I found out online if they aren't set to "Auto" you'll be limited to Mode 2 on all devices. So I set them to Auto, reboot and the BIOS lists the devices:

Primary Master: Hard Drive
Primary Slave: Hard Drive
Secondary Master: CD-ROM
Secondary Slave: CD-ROM

Boot into Windows and the hard drives are now running at UDMA Mode 5. I reran experience index in Windows 7 and the Hard drive rating increased ~30%.

[bolomkxxviii]

Oddball BIOS can create all kinds of headaches. Older HP computers have given me more than a few grey hairs.