There's usually a little number one or indicator triangle that you line up the IDE cable's colored stripe with.

My computer teacher teached me a very simple method to connect pc cable correctly

Put red line close to red power cord

Put red line close to number 1 and 2

I mark the number for you

nd22 wrote:

Hello to all! I started to build a slot 1 system after I acquired an Abit BX6 2.0 motherboard together with an Intel Pentium 3 450 processor. I installed a stick of ram, a Radeon 9250 video card and a floppy to see if it starts OK. The machine starts just fine with an MS-DOS 6.22 and has no problems. However I can not connect a CD-ROM or a hard drive because they are not recognized by the BIOS! I am fully aware that I need an ATA33 cable and I got one however there is no PIN1 marked on the board or on the cable! The cable goes both ways in either the motherboard or the CD-ROM and I can not determine which orientation is right!I attached some pictures maybe someone can provide assistance! Thank you!

Apart from the above mentioned tips you also need to be aware of the master/slave/cs settings on IDE drives.
Usually a single drive on an IDE cable needs to be bridged as master, tho CS (cable select) may also work.
Cable Select can in theory be neat, it means that the drive furthest out on the chain will be master automatically.
Tho in reality its better to jumper the drives correctly.

And congratulations on a great motherboard, BX6 2.0 is one of the great ones.
Manual (wich includes pinouts for all the connectors), BIOS and other info can be found here:
https://soggi.org/motherboards/abit/BX6.htm

Thank you all and especially Ponjiayulady! I did put the red as suggested in the picture provided by Ponjiayulady and entered BIOS in the IDE hard disk detection menu to start manual detection of the drive but no luck! I tried with the CD-rom only using master/slave and cable select jumper settings but no luck either! The bios is at the version QR which is the latest! I tried with 3 different CD-ROM drives that I previously tested and I know to be good to no avail!
I put the lone connector on the IDE cable in the IDE1 connector on the motherboard; the closest IDE connector was used for the hard disk drive and the farthest for the CD-ROM! Does it matter which connector goes where or not? Should I put the cable the other way around? I jumpered the drive to master and the cd-rom to slave but still nothing!

Try to connect IDE like this way
Closest IDE connect to CD-ROM, set jumper to Slave
Farthest IDE to Hard Drive, set jumper to Master

It works! All I had to do is set in the standard CMOS menu all options regarding the IDE controllers to AUTO and is no longer required to enter IDE detection menu - it simply detected the 80gb western digital drive and the CD-rom automatically! Now for the horror of the community I installed Windows millennium on it - actually for the out of the box USB support 😊 - and it installed just fine. When I tried to install the chip-set drivers a message appeared that inf update is not necessary! I installed the video drivers and right now I am at the audio drivers. I selected Creative live 5.1 card.
The drive are setup this way: the farthest is the optical unit and is set to slave; the closest is the WD drive and is master.