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General Motherboard Features

Legacy Ports

This should not matter to most home users because legacy ports like serial and parallel ports are no longer in use, except in niche applications by engineers and geeks. Despite my love for USB and everything hot-plugable; PIC and microcontroller programming (who doesn't love Kermit???), Cisco routers and switches as well as a host of other professional-grade devices still use these ports.

Fortunately, a host of motherboards still offer legacy port support if only in the form of header pins. However, if you do not use them, these ports waste PC resources like IRQs and DMA channels. So, if your motherboard comes with these legacy ports and you don't use them, do yourself a favour and disable them in the BIOS to free up those resources.


Multi GPU Technology

I could talk all day about this but I'll apply the KISS rule here. There are two camps in the Multi GPU war - NVIDIA with Scalable Link Interface (SLI) and ATI with CrossFire. No matter what they call it, both technologies allow you to install two graphics cards onto the motherboard for twice the graphics processing power (or so they claim). More importantly, it lets them sell twice as many cards than they would if the motherboards only supported one graphics card.

Any motherboard that support either one of the two Multi GPU options must come with two 16X PCI Express slots. However, this is only the slot size. It does not mean the cards will actually run at 16X. In many motherboards, the slots are set to run at 8X when two cards are installed. Needless to say, motherboards based on NVIDIA chipsets will only support NVIDIA's SLI technology, while ATI-based motherboards will only support ATI's CrossFire technology. However, there are rumours that AMD (which is now ATI's parent company) will make CrossFire an open standard for use in other platforms without licensing issues.

Which should you choose? It is really up to you. Both SLI and CrossFire are designed to do the same thing. NVIDIA used to have a better implementation using SLI bridge to connect the two identical cards while ATI requires you to purchase a separate CrossFire Edition card to connect with a regular Radeon card. But this is now a moot point as ATI has started implementing the same bridge system in their new cards.


PCI Express Lanes

PCI Express slots support up to 32 lanes, each of which is a dedicated serial interconnect. Each lane is capable of delivering 250MB/s of bandwidth, giving PCI Express (which is currently limited to a maximum of 32 lanes) a maximum bandwidth of 8GB/s. However, the PCI Express x16 slot is the largest slot adopted by the industry.

However, a PCI Express x16 slot does not mean that all 16 lanes are functioning. PCI Express slots allow for downward scaling. So, a PCI Express x16 slot can scale down to 8x, 4x, 2x and 1x. You should keep this in mind because not all PCI Express 16x slots will always run with all 16 lanes operational, even if the graphics card supports 16 lanes.

This is especially true in motherboards that support multi GPUs. Most multi GPU motherboards (with a few exceptions) reduce the number of operational PCI Express lanes by half to x8 when a second graphics card is installed. This gives you only 8 lanes per graphics card.

With that said, I wouldn't worry too much about this because most multi GPU setups transmit their data over a bridge interconnect, rather than the PCI Express bus. Only a few (cheaper) multi GPU setups use the PCI Express bus for inter-GPU communication. Even so, it is not really a big deal as graphics performance is not significantly affected by the PCI Express bandwidth. I just want to remind you that while the motherboard may claim a certain PCI Express slot, electrically it could run with fewer operational lanes than advertised. So keep your eyes open, eh?


Debug LEDs

Well, this is one of those little features that make my life as a lowly tech engineer that much easier. It is an LED array that lights up with numbers. If anything fails during startup, the LED will give you a code indicating the point of failure. This makes troubleshooting much simpler, so if you repair your own computers, get yourself a motherboard with debug LEDs. Seriously, they're pretty nifty things to have around.


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