Pros and cons of integrated motherboards

What is an integrated motherboard? Every motherboard is integrated to a degree. But there are positives and negatives to integration. So not everyone sees an integrated motherboard as an advantage. Here’s what it means and why it matters to you.

Today, an integrated motherboard usually means all the functionality, including video, network, and all common I/O are built right onto the motherboard, with no need for any cards in expansion slots. This allows for a smaller and cheaper system.

What is an integrated motherboard?

what is an integrated motherboard
This motherboard shows a high degree of integration, with USB 2.0, USB 3.0, video, networking, and audio all built right onto the board itself.

Early computers provided minimal functionality on the motherboard itself. Instead, most of the functionality came from plug-in cards that plugged into an expansion bus. This let you buy a computer and then upgrade it over time just by plugging in a card that provided additional functionality.

IBM adopted this approach on its original IBM PC. The first IBM PC provided minimal functionality on the motherboard: Just a CPU, a nominal amount of RAM, a keyboard port, a cassette port, some ROM chips that provided basic functionality, and the programming language Basic. For anything else, you needed a board that plugged into an expansion slot.

The expandability was great. Well, until you ran out of slots. And you did run out of them pretty quickly. Everything you’d want came on an expansion card, and you only had room for five of them. It also added cost, and it wasn’t the most efficient use of space either.

So when IBM PC clones came along, they took two different approaches. Some copied IBM as closely as possible. Indeed, some early IBM PC clones were almost bolt-for-bolt copies. Others copied the form factor and overall philosophy but would make subtle changes if they could save a few dollars. But others took a different approach, building some of the more popular functionality into the motherboard. This allowed companies to make their systems smaller and cheaper, while still running all of the same software.

Disadvantages of integrated motherboards

This non-integrated 286 motherboard from around 1990 only has a keyboard connector built in. All the drives and even a mouse had to plug into an expansion card.

The disadvantage of integrating everything together so tightly was that if something broke, repairs were much more expensive. If your printer port went bad in an IBM PC or a close clone, you just swapped out the card. It was an easy and cheap repair. On an integrated system, you had to disable the built-in part that broke, then plug in a card, if you had room. If you didn’t have room, or couldn’t disable the broken part, you were looking at an expensive board-level repair, or swapping out the whole motherboard. On a non-integrated system, you were looking at a $35 repair. Swapping a motherboard might cost several hundred at the time.

Here in St. Louis, some of the prominent independent computer stores at the time would run in-your-face ads in the local papers talking about the evils of those integrated systems. What they said wasn’t wrong. But they did overestimate how often you actually had to replace bad components. And you have to admit, saying your computer is cheaper to fix when it breaks is a bit of an odd marketing message.

The inevitable integration

Over time, the pace of integration marched on. And by the time Pentium computers became mainstream, even the motherboards those clone shops sold had a pretty high degree of integration. They still looked like 8-slot IBM PC/AT clones from the outside, but the disk controllers, serial and parallel ports were all on the motherboard, with ribbon cables connecting them to brackets in the expansion slots. Then ATX came along and ended the charade.

After that point, the only advantage of non-integrated systems was in the case when you had different classes of components. Usually, but not always, it was the cheaper stuff that got integrated, not the performance stuff. If you wanted performance, you’d look for a board that left out the parts you didn’t want, or you’d disable the built-in stuff and plug in the high-performance parts you wanted.

Advantages of integrated motherboards

Motherboards started integrating those components because of cost. At one time, the disk controllers, serial, and parallel ports all sat on individual cards. Eventually, companies brought them all together onto a single card that cost half as much as all those individual cards, and only took one slot. But when that card cost $25 and that functionality could be put on a motherboard for $10, it made sense to put it on the motherboard. Over time, that cost decreased even more.

Today, inexpensive boards integrate it all, providing video and networking in addition to disk controllers and ports for things like printers. That’s one reason you can get a decent computer for around $200 today. All the cheap, good-enough functionality fits right into the CPU itself, or one or two chips that sit right next to it on the board.

Over time this has increased reliability, not decreased it. When a cheap system goes bad, it’s more frequently due to a power supply or a hard drive or a software issue than the motherboard. Today’s computers are faster, cheaper, and more reliable than their ancestors from two or three decades ago.

Why you might not want a fully integrated motherboard today

what is an integrated motherboard?
This high-end motherboard doesn’t integrate video. Two discrete cards on the right provide video functionality. But even on this board, USB, networking and audio are built in.

The main reason you might not want a fully integrated motherboard is performance. The video integrated on motherboards always has low-end to middling performance, at best. If you want something better than middling video performance, you want a plug-in card. Networking often is the same way.

But that’s easy enough to overcome. If your system has integrated video, the system disables it when you plug in a separate video card. So you can always start out with integrated video, then upgrade when you need more performance and your budget permits it.

Also, integration isn’t all bad. USB is USB, and SATA is SATA. There’s no advantage to putting USB or SATA on a plug-in card, except to add a newer version to a system that didn’t originally come with that newer version on the motherboard.

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