The North Bridge Strap

By unlocking the FSB from the RAM, you can set the RAM speed and FSB to your liking.

Fairly new to Intel-chipset boards is a feature known generically as the north bridge strap—Asus calls it the FSB Strap to Northbridge and Gigabyte calls it the System Memory Multiplier—and it can throw us old-timers for a loop. The north bridge is actually its own little processor, which, on Intel chipsets, is tied, or “strapped,” to the front-side bus and memory. It’s possible to change the speed of the strap—both Asus and Gigabyte, for example, let you manually select strap speeds from 200MHz to 400MHz.

There are two practical uses for this. First, by manually setting the speed of the north bridge strap, you can change the memory clock speeds available on the board. As mentioned above, simply increasing the front-side bus speed will automatically increase the speed of the memory—perhaps far beyond what your module is rated for. By notching the strap down, you can get your RAM operating within spec while leaving the FSB at its overclocked state. Why not just let you pick the RAM speed you want and be done with it? The theory is that the straps are already preconfigured to offer the best performance ratios, which are preferable to those you set on your own.

Selecting a lower strap but the same RAM speed may help you push the front-side bus speed higher during an overclocking session.

The second purpose of the strap: The internal clock in the north bridge will gradually tick up as you increase the front-side bus of your system. It’s somewhat similar to the gear ratios in a car. As you rev up the front-side-bus speed, the rpms of the north bridge can get out of spec and cause a crash. The strap will adjust the speed of the north bridge clock independent of the FSB. The general rule of thumb for overclockers is to use the lowest strap available that runs your RAM at the speed you need. This should enable higher front-side bus overclocks.

The upshot of this is to run in auto mode if you’re not overclocking and leave it to the board engineers. If, however, you are overclocking and seemingly hitting a front-side bus wall that no amount of voltage will address, try lowering the north bridge strap to see if you can push the FSB even higher.

Ganged Activity

If you’re an AMD user and you’re confused by all this north bridge strap stuff, you can just ignore it. Since Phenom CPUs feature the memory controller directly in the CPU core, there is no memory controller strap to futz with. What is confusing is the ganged or unganged mode available in Phenom boards. Phenom CPUs feature two separate memory controllers that can be run ganged or unganged. Generally, you’ll want to run as unganged to let the controllers operate independently for best performance.

Out of the Skew

Tweaking the skew for RAM lets you compensate for the minute signal distortion that occurs with high-speed parallel interfaces.

Some motherboards have begun offering the ability to tweak the “clock skew” for RAM. In a nutshell, clock skew is the variation in speed of a module’s individual signal paths to the memory controller. Skew is the result of the signal distortion caused by the traces in the motherboard, the cleanliness of the power going to the board, and the RAM that’s in use.

Tweaking the skew settings can help increase stability when you’re pushing the chipset and RAM to its limits by overclocking. It’s a game of trial and error with skew settings, but if you’ve got the time and energy, it could help you achieve the few extra megahertz you were hoping to get out of your system—just be ready to roll up your sleeves and run the POST, crash, reset, POST routine. If you’re not overclocking, however, you can just ignore these timings.

Beyond the BIOS: Exploring the Pre-OS Environment

When the BIOS is finished prepping the hardware, it doesn’t necessarily have to hand control over to the OS. Instead, many companies are now inserting a pre-OS, or preboot, environment on their boards that the PC can boot to before the OS.

These environments are stored on small bits of flash RAM embedded on the motherboard and can contain a basic Internet browser, Skype client, and even the ability to access your Outlook email and contacts. Although referred to as a pre-OS, the majority of these environments are embedded Linux.

The feature has long been found in notebooks, but it’s now migrating to desktop motherboards. Currently, Asus is the primary adopter of the pre-OS and has it in many of its motherboards. In our experience, it’s a novelty that can occasionally be useful—say, for example, you need information from the Internet faster than you can wait for the OS to load. With Asus’s ExpressGate pre-OS you can be in a browser in one minute instead of five. Granted, that’s a rare need, but we can see a pre-OS browser being useful for, say, downloading utilities, drivers, or fixes to a broken or infected OS on the hard disk—though currently, none of the implementations we’ve seen allows you to save files to your machine.

Next: CPU Tweaks