BIOS tips and tweaks for speed and extra functionality

4th Nov 2009 | 10:20

BIOS tips and tweaks for speed and extra functionality

Unlock the secrets of your PC's BIOS

Introduction and boot management

The typical BIOS set-up program is intimidating in the extreme, packed with technical options that could badly damage your PC if you don't use them correctly. And so most people make do with the default settings.

That approach guarantees your system will work, but it also means that it will never deliver its best performance. Learn a little more about the options on offer and BIOS tweaking won't seem as scary.

Our detailed guide to each BIOS menu explains the settings you can change, and the ones you really shouldn't. With a little experimentation you'll be able to discover useful information about your system, cut its boot time, extend battery life on a laptop and overclock your PC for a performance boost.

Meet your BIOS

Most BIOSes display a message at boot time telling you how to load their set-up program. Typically this is done by pressing [Del] or [F2]. If your system boots into a full-screen logo then try pressing [Tab] immediately to see any set-up messages, or check your system documentation for more clues.

Once you've launched the BIOS program then you'll probably first see the Main menu. This usually contains only some legacy settings and a few options that the BIOS creator couldn't fit anywhere else, but these can still be useful and the menu is definitely worth a quick look.

Date and time

Normally you can leave this setting alone, but if the clock often resets to some wildly different time then your motherboard battery may be failing. Check your documentation to find out what type it uses, and order a spare. Better still, buy one now, just for emergencies – popular lithium cells like the CR2032 cost under 50p.


Floppy disk

Even now many BIOSes have floppy-related settings. If you have a disk but don't use it, disable these for faster boot times.

IDE/SATA channels

You may have a menu that shows the IDE and SATA drives you've connected to your system and the channels they're using, which is particularly useful if you've installed a new drive and want to be sure it's recognised. If you don't see an attached drive, make sure that the channel isn't disabled (select it in the BIOS and look for options), that the drive is properly connected and that your IDE drives have their master/slave switch set appropriately.

Configure SATA as

Set up your SATA controller to run in one of three modes: RAID if you're combining two or more drives in a RAID configuration, AHCI to enable additional SATA features or IDE for the best compatibility.

Some people claim enabling AHCI will speed up your hard drive, but if there's a difference then it'll be extremely small (and it could actually slow you down). What's more, you may find that Windows won't boot properly, forcing you to reinstall it. We'd leave this alone unless you're very sure that AHCI will help in your particular situation.

IDE Detect Timeout

Some motherboards boot so quickly that IDE drives don't have time to spin up, and so aren't initialised. To avoid this the boards wait for a period of time known as the IDE Detect Timeout. If you have an IDE drive that isn't always detected then increase this value for more reliable results.

The Boot menu includes options to define what happens when your PC starts. Some BIOSes hide these settings away in the Advanced menu.

Boot device priority

Defines the order in which the BIOS will look for bootable drives. Set the first device as your hard drive for quicker boots, but move your DVD drive to the top of the list if you need to boot from your Windows disc, for instance.

Boot order

Full-screen logo

Displays a logo which annoyingly covers up your BIOS status messages. We'd turn this setting off to avoid missing anything important, and also to avoid the fraction of a second that it adds to your PC's boot time.

Hit [Del] message display

Allows you to disable the message explaining that pressing [Del] will get you into the BIOS set-up program. This might be useful if you're dealing with your kids' PC, where you don't want them tinkering, but be sure you don't forget how to get into the BIOS yourself.

Wait for [F1] if error

Tells the BIOS to wait for you to respond to any boot problems found before it continues with the set-up process. That's normally a good thing, but if it's a minor issue that you already know about – or alternatively if you're using a server that doesn't have a keyboard – then it may be preferable to disable this setting.

System information

A handy list of details on your PC hardware, including CPU type and speed, installed RAM, BIOS version and perhaps the build date.

If your BIOS is very old then upgrading it may add more features and improve compatibility with new hardware and software, but if the upgrade fails then your system may become irreparably broken.

Check to see if your motherboard has any way to recover from a trashed BIOS, and back up any valuable data before attempting an update.

System info

Power controls and hardware monitor

Power is the section where your motherboard shows off its green credentials with a range of power-saving and sleep-related settings.

Suspend mode

Also known as ACPI Suspend Type, this setting decides how Sleep mode will work on your PC. Set this to 'S3' to turn off almost every device, meaning that the system will use very little power (for example, only 8W on our test PC).

If you have problems getting devices to work after your PC wakes up – and driver updates don't help – then you could use 'S1' Suspend Mode (or 'S1 Only') instead. This keeps more devices awake and so improves compatibility, but at the cost of much greater electricity consumption – 195W on our test system.

Repost video on S3 resume

Re-initialises the video BIOS after waking up from an S3 sleep. Disable this and your PC might wake more quickly, but you also might find that there's nothing on the display – a real problem if there are important documents you need to save. If you disable the setting, test it first to make sure that your video card resumes properly.

Power on by RTC alarm

Uses the real-time clock to automatically fire up the PC at the time of your choice.

Power on by PS/2 keyboard

If you've got an old-style keyboard that uses a PS/2 connection (not USB), this setting lets you turn on your PC just by pressing a key.

Power on by PCI/PCIe devices

Also known as 'Wake-On-LAN', this is most useful for waking up your PC when it detects network activity. Set everything up properly and you can even start your PC over the internet. Combine this functionality with a remote access tool like LogMeIn in order to access your files when you're away from home.

Also known as PC Health Status (and sometimes found as a submenu under the Main, Power or Advanced menus), this is where you'll find details on component temperatures, voltages and fan speeds.

Overclockers should check this section to ensure their tinkering isn't pushing their system too far. If you're experiencing odd PC problems that may be caused by overheating, you'll want to check here too.

Voltage monitor

Displays the voltages of your PC, CPU, memory, system bus and more.

Temperature monitor

Keep an eye on your CPU, MB (motherboard), NB (Northbridge) and SB (Southbridge) temperatures here. Every system is different, but our i7 920 system varied from around 30 to 50°C depending on setup and load. There are normally options to prevent overheating, too.

For example, our test PC had an 'overheat protection' setting that would automatically turn the PC off if the Northbridge or Southbridge exceeded 90°C. If your PC sometimes turns off unexpectedly then this could be the cause.

Fan speed monitor

This section tracks the current speed of your PC's fans.

Fan speed control

Most BIOSes have their own ways of varying fan speed according to circumstances. On our test system, for instance, we can set a particular fan to 'User mode' and then define the temperature when it will hit full speed (60°C by default).

Asus boards also provide something called Q-Fan, which lets you choose your fan speeds from one of three profiles: 'Silent' optimises your fans for minimal noise, 'Turbo' is noisy but keeps your system as cool as possible, while 'Standard' is somewhere in between.

Advanced settings and manual overclocking

The Advanced menu might more accurately be called Miscellaneous, as it's crammed with general options relating to your CPU, chipset, USB controller, C1E support: This technology saves energy by reducing CPU power when there's little work to do. Leave this on to save power and extend battery life, but turn it off to help with any overclocking you're doing.

Intel SpeedStep

This setting – known as 'Cool n Quiet' on AMD systems – saves power and reduces fan noise by cutting your CPU's voltage and clock speed when it has little to do.

Once it's enabled, Windows Vista users can choose to reduce their maximum CPU power ('Control Panel | System and Maintenance | Power Options | Change Plan Settings | Change Advanced Plan Settings | Processor Power Management'), which is perfect for extending a laptop's battery life.

Virtualization technology

Allows virtualisation tools like Microsoft Virtual PC, VMware Workstation and Sun's VirtualBox to benefit from additional processor support.

Intel VT-d

Allows compatible virtualisation tools to directly access hardware devices on the host PC, which can greatly improve performance. We've seen reports that it can also mess up your PC in unexpected ways, though, so leave this disabled unless you need it and know exactly what you're doing.

Onboard devices configuration

Sometimes available as a separate menu called Integrated Peripherals, this lists devices integrated into the motherboard (audio, network ports, FireWire ports and more) and lets you turn them off.

Disable unused devices here to reduce the chance of hardware conflicts and prevent the BIOS and Windows wasting time by initialising them and loading their drivers. Or, if you find a network port or other device that doesn't seem to work, check here to see if it's disabled before you assume you've got a motherboard fault.

Just about every BIOS comes with an overclocking section, the area where enthusiasts go to ramp up their CPU or RAM speed. Take it too far and this can make for an unstable system, shorten the life of some components or even fry them instantly, but treat your overclocking options with caution and respect and they'll usually deliver a welcome free performance boost.

CPU level up

Overclocking used to mean lengthy trial and-error periods as you tried to figure out the best values for a stack of cryptic settings. Luckily, the motherboard manufacturers have now stepped in with a range of ideas on how to simplify the situation.

Our Asus-based test system uses a feature called 'Ai Overclocking'. If we select CPU Level Up, it provides the option to increase our CPU performance from the normal 2.66GHz i7 920 to a 2.93 GHz i7 940 setting, just by selecting it from a menu.

Ai Overclocking then steps in and adjusts the more technical settings to make this happen. It worked perfectly when we tried it, with benchmarks showing our CPU speed up by 10 per cent. But if you have stability problems, or your PC temperature rises drastically, then change the setting to 'Auto' and everything should return to normal.


Memory level up

Similar to CPU Level Up, this option displays higher performing RAM standards, lets you choose one, and then automatically sets your RAM timings to match. Again, change the setting back to Auto to undo any changes.

Ai Overclock tuner

Leave this set to Auto and the CPU Level Up and Memory Level Up options will work just as we've described. If you want to tweak the settings yourself then set Ai Overclock Tuner to 'Manual' and start exploring the more detailed options that we'll describe next.

The overclocking section in your BIOS will provide a number of useful manual settings. If you're willing to take the risk of overclocking in return for a little extra performance (and you know how to reset your motherboard's CMOS RAM in case your system locks up completely) then here's how to get started.

CPU Ratio setting

Your processor's clock rate is determined by multiplying an external clockspeed with a CPU Ratio, or multiplier.

Our test Core i7 920 system has a 133MHz base clock (BCLK) speed and a multiplier of 20, giving a CPU clock rate of 2.66GHz. Increasing the multiplier by one would provide an immediate five per cent speed gain – if it wasn't for the fact that most CPU multipliers are locked. So unless you've got an unlocked CPU, like an Intel Extreme, you'll need to try something else.

Manual overclocking

BCLK frequency

Our i7 920 test system allows the base clock frequency to be changed from 133 to whatever we'd like to try, which will proportionally ramp up the speed of our CPU and RAM.

Exactly what you'll achieve here depends on your hardware, but our Scan test PC handled an impressive 50 per cent increase in BCLK and still appeared stable. Look for an FSB (Front Side Bus) setting on other systems, which has the same effect.

FSB Memory Clock mode

The problem with changing your base clock or FSB speed is that it affects everything else too. If your RAM can only handle a five per cent overclock, say, then your attempts will fail, even if the CPU could do considerably more.

Set the FSB Memory Clock Mode to 'Unlinked', though, and FSB changes will no longer affect your RAM – so you can now overclock your memory and CPU separately.

If you don't have this option, then there should be an 'FSB to RAM Ratio' or other memory divider setting that reduces the impact of any FSB changes. Alternatively, you may be able to set the memory frequency directly.

Processor NB Frequency multiplier

Increasing the FSB affects components like the Northbridge as well as your RAM, and as these often fail early they can quickly bring your efforts to a grinding halt. Dropping this multiplier (and similar settings) lets you reduce the Northbridge frequency a little, which may allow you to increase the FSB further than you would do otherwise.

DRAM Timing control

Your RAM makes use of a number of timing delays to keep everything running smoothly, and you'll find these listed in a submenu within your overclocking section. Reducing these timings will improve performance a little (perhaps two to four per cent), but may make your system more unstable . AMD has a helpful article explaining more at

CPU voltage

If your overclocking efforts don't produce the improvements you need, then increasing the CPU, memory and other chipset voltages may help. On the other hand, going too far might fry your hardware beyond hope of repair.

So do your research: check the specifications for your memory and processor, and browse overclocking forums to see what others are doing before you start. If you still want to try this, then increase voltages by small increments, while monitoring your system temperature.

However far you take your overclocking, keep in mind that any resulting instabilities may take some time to appear, and so it's important to stress-test your PC before you finish. Install a tool like Prime 95, Orthos or OCCT and leave it running for 24 hours. If there are no lockups then your system is stable and ready to start some serious work.

Thanks to Scan Computers for kindly providing us with a 3XS Triad: a Core i7 PC built around the Asus Rampage II Extreme motherboard. Thanks also to our colleagues at for the BIOS images.


First published in PC Plus Issue 287

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