Standard tower PCs have ample room for add-on components like graphics or audio cards. Slim form-factor PCs sacrifice extra component space in exchange for a smaller total size. Low-profile graphics cards are roughly half as tall as a standard graphics card, allowing them to fit into the smaller component space in low-profile PCs.
The primary difference between standard profile and low profile cards is in their height. Standard profile cards can be up to 4.2 inches tall. Low profile cards are limited to a maximum height of 2.536 inches. The smallest standard of low profile graphics card, designated MD1, is limited to a maximum length of 4.795 inches. Longer low profile cards are designated MD2 and can not exceed 6.674 inches in length. No standards limit the width of low or high profile graphics cards. Some graphics cards with fan assemblies may be wide enough to block access to nearby PCI slots.
Low profile graphics cards draw less power from the motherboard than standard graphics cards. Low profile graphics cards draw 25 watts while standard cards draw 75 watts. Like standard cards, low profile cards may draw additional power through a direct connection to the computer's power supply. Low profile cards typically require less power than standard graphics cards because they are frequently slower and less powerful than standard card.
Low profile graphics cards use smaller fans than standard cards because of their smaller size. This limits their ability to cool a graphics card's graphics processing unit. Low-profile cards need to use slower processors than standard cards to avoid producing the high level of heat that more powerful processors create, thus keeping the heat within a range that the card's smaller fans can dissipate.
Low profile graphics cards connect to a computer's motherboard in the same slot that standard graphics cards use. You can connect a standard profile mounting bracket to a low profile card to mount it in a case designed for standard graphics cards. Regardless of the bracket type, you cannot mount a standard graphics card in a case designed for low graphics cards due to the space limitations of the case.