Demystifying the Graphics slots,  PCI Express slot or AGP slot. How to select the proper video card for your computer or your motherboard.

• PCI Express16 slots is the new type of slot on new Pentium 4 and Athlon 64 motherboards. They are about 8.5 cm long (lengh of the slot, not the outer length)
• Depending on the age of the motherboard it may have an PCI Express slot, AGP 1x slot, AGP 2X slot, AGP 2x/4X slot or AGP 4x/8X slot. (AGP 1x slot will be refer to in the motherboard manual as "AGP slot" as there was no other type of AGP slots in those days),   AGP slots are about 7cm long.
• Some motherboards including Intel i845 or 865, 875 chipsets based motherboards will not accept AGP 2x cards and they may even damage the motherboard. if you install the wrong type AGP card.
• Most video cards will accommodate two or more AGP slot types. For example current GeForce FX 5200 card by Jaton will support AGP 2x/ 4x or 8x slots.
• Also most motherboards will (if it has an AGP slot) will accommodate two or more types of cards. For example all current motherboards will accommodate AGP 4x or AGP8x type card. (Even though it may not support the additional data band width of AGP 8x)
• Most of the new motherboards have locking mechanism for card at the far end of AGP slot. Do not damage that. Follow the instruction on the motherboard manual or take care to study the locking mechanism and release the lock when installing or removing cards.
• Some old AGP cards in early days had a jumper or dip switch to change between AGP 2x and 4X modes. If you are using one of them make sure you set it correctly.

PCI Express16 slot

Partial  view of the motherboard with AGP 2x/4x slot (Brown)   and adjoining PCI slot. (White). This picture was taken from Abit KT7A motherboard

View of the complete motherboard. You can see the brown colour AGP slot almost in the middle of the picture and several PCI slots to the left.