54 | MAXIMUMPC | NOV 08 | http://www.maximumpc.com
Tweaking Your Memory
The days of just selecting your RAM speed are gone. A modern BIOS exposes
enough RAM controls to give even the most seasoned hobbyist a headache.
For the die-hard enthusiast though, those knobs and switches also mean
something good: control
TIMING IS EVERYTHING
Poke around the BIOS of a budget board or
an OEM machine and you’ll fi nd it as easy to
understand as “The Pet Goat.” Heck, even an
enthusiast board from three years ago could
be understood by most advanced users, as the
memory options were as simple as DDR333 or
DDR400. Today, we’re not even sure that the en-
gineers who write BIOSes fully understand all
of the options available. Take, for example, DQS
Drive Strength or Process On-die Term B. Huh?
Both actually relate to the ability to tweak and
tune your RAM to higher frequencies, but for
the most part, you can ignore them unless you
really want to spend an entire aft ernoon setting,
crashing, and resetting your machine.
Fortunately, the fundamentals are still
as valid today as they were a couple of years
ago: Column Access Strobe Latency (tCL), Row
Access Strobe to Column Access Strobe Delay
(tRCD), Row Access Strobe Precharge (tRP), Row
Access Strobe Precharge and Precharge Delay
(tRAS), and Command Rate or Command Per
Clock (CMD). In the BIOS, you’re able to tweakthe timing for each
of these settings to
aff ect RAM perfor-
mance.
If you think of
RAM as a collection
of books in a public
library, each timing
setting relates to
an element of the
librarian fulfi lling
your request for a
particular tome. The
timing is described
in clock cycles, so
a lower number
equals a faster time.
The tRCD set-
ting, for example, describes how much time the
librarian has to get to a certain row on a shelv-
ing column. Set it too low, and she can’t get to
the row where your desired book resides.
Say she reaches the row; the tRAS deter-
mines the time the librarian can linger therefi nding your book. tRP is how much time the
librarian has to get from the row she was at to
the bottom of the ladder.
tCL is how much time she has to move
between the diff erent shelves of books. Setting
it too low would be like asking her to push a
30-foot rolling ladder 100 yards in 2 seconds.OLD TECH, NEW TWEAKS
When the BIOS is fi nished 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, en-
vironment on their boards that the PC can boot to before the
OS. These environments are stored on small bits of fl ash RAM
embedded on the motherboard and can contain a basic Inter-
net 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, Asusis 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.BEYOND THE BIOSExploring the Pre-OS Environment
You often have to set performance RAM manually for it to hit its rated
speed and timing.