Why does not your Computer Boot? Part I

There is often a problem when you turn the power on and a green light is flashing or steady on the monitor, but your computer does not boot. And a system case and monitor are also connected by a cable and there is not any message “No Signal” on a screen.

This problem appears in two ways: there are some inscriptions on a screen but operating system does not boot; or the screen is dark and something beeps or flashes in a system unit.

The first problem is rather simple – probably, BIOS could not find any boot records on those devices that are listed in its parameters. For example, there is a floppy in a drive containing general data – BIOS has detected a device that is ready for system booting and has transmitted a control to it, but there is no boot record on a floppy.

It is also possible that the parameters set in BIOS are inaccurate. For example, you have changed a hard disk but have not identified it in BIOS.

It may also happen that the power battery of BIOS has run out. This problem can also be solved. In this case all BIOS parameters automatically take default values and “CMOS battery failed” (or “CMOS battery state low”) may appear on a screen. Most default parameters in modern BIOS have the value “Auto” that enables automatically setting the most appropriate values and also determining the available IDE-devices. There is no automatic default determining of IDE-devices in outdated models of BIOS but you can also try to boot your computer by setting the value “Auto” for all Primary and Secondary Devices manually.

Security and Warnings

Here are some warnings of computer overclocking:

  • Do not attempt to overclock you computer to the maximum. If you damage a processor that is under a warranty service during overclocking, it would unlikely be changed even if it was initially defected.
  • Do not change BIOS configuration on brand computers. If a case of your computer is sealed and changes in BIOS have led to irreversible consequences, you should contact the Service. The only exceptions are computers with motherboards that contain the auto reset technology of BIOS settings.
  • Be careful with overclocking. If you have a value scale, perform all changes consistently: increase the current value by one minimal value and see how your computer operates. If everything is normal, you can increase the parameter value by one more step. But if there are some problems, you should return to the previous value at which your computer operates normally. This process may take a long time.
  • Do not trust your friends in their previous successful overclocking.

The Sequence of Boot Device Search. Part III

Various types and versions of BIOS may use different parameters. For example, “A, C” – the first booting from a floppy-disk and the second booting form the first hard drive; “C Only” – booting only from the first hard drive; “C, CDROM, A” – the first booting from the first hard drive and the next ones from CD-ROM and from A; “D, A, SCSI” – the first booting from the second hard drive and the next ones from a floppy and from a device connected via SCSI-controller.

Each user can individually set the sequence of device bypass during booting. You can do the following: do not set a floppy-disk as the first device (a value Floppy or FDD). Remember to remove a floppy with no boot information on it from a drive before switching on; otherwise the computer booting will be interrupted pending a boot floppy in a floppy drive. To solve such problem, click any button after a floppy has been ejected from the drive. if there is no boot sector in CD-ROM, it is just ignored.

After all parameters are set, save changes in BIOS and reboot your computer. Enter the main menu and select Save&Exit Setup. A window appears that warns you about parameter changes and an attempt to exit BIOS Settings. When you press Enter or Y (Yes), all parameters will be saved and a computer will automatically reboot with new parameters. When you press Esc or N (No), you will return to the main menu of BIOS Settings.

To exit BIOS without saving any changes, select “Exit without Saving” in the main menu and press Enter or Y in the information window. Your computer will continue its booting with the previous parameters.

The Sequence of Boot Device Search. Part II

If there are no boot records, there is the information on a screen that no boot devices had been found (No value) or the search is carried in the other devices (Yes value).

The parameters defining boot devices may have the following values:

  • Floppy – booting from a floppy;
  • HDD-0 (IDE-0) – booting from the first hard drive that is connected as Primary Master;
  • HDD-1 (IDE-1) – booting from the second hard drive that is connected as Secondary Master;
  • HDD-2 (IDE-2) – booting from the third hard drive that is connected as Primary Slave;
  • HDD-3 (IDE-3) – booting from the fourth hard drive that is connected as Secondary Slave;
  • LAN (or Network) – booting from the network;
  • SCSI – booting from a device connected via SCSI-controller;
  • LS/ZIP – booting from ZIP-device;
  • LS/MO – booting from magneto-optical disk;
  • CD-ROM – booting from CD-ROM;
  • USB (FDD, HDD, CD-ROM) – booting from a device connected via USB-port with an appropriate interface;
  • Enable – a parameter is off;
  • Disabled – a parameter is used for free device search.

Of course, you do not have to install all the listed devices; the most commonly used values are for booting from CD-ROM, hard drive and floppy.

If you have several hard drives with an operating system on each of them, you can set the sequence of search of such devices. But in this case you have to know in what way each drive is connected via IDE-loop. Quite frequently, a user has got one or two hard drives but he does not know how they are connected. If you have got one hard drive, you should only set a value HDD-0 (IDE-0) regardless of its connection. If you have got two hard drives, set a value HDD-0 (IDE-0) for the first parameter and HDD-1 (IDE-1) for the second one.

The Sequence of Boot Device Search. Part I

After you have identified all accessible IDE-devices, you can start creating a sequence of device search that may contain boot records or some media with them. Go to “Advanced BIOS Futures” (or “BIOS Futures Setup”) section.

As a rule, the way of navigation and the keys of quick access to parameters are described at the bottom part of BIOS Settings Window or to the right of it. To toggle between the parameters inside one section, use the arrow keys (→, ←, ↑, ↓), to enter a section use Enter button, to exit a section use Esc button, to search values accessible for this parameter use -/+ buttons on the additional numeric keypad (or Page Up/Page Down buttons).

The further actions will depend on the type and version of BIOS: in outdated versions such parameters that define the types of devices with boot sections are located directly in “Advanced BIOS Futures► Boot Sequence” (“System Boot Sequence).

The following parameters are used for specifying boot devices:

  • First (1st) Boot Device;
  • Second (2nd) Boot Device;
  • Third (3rd) Boot Device;
  • Fourth (4th) Boot Device;
  • Boot Other Device – choosing an additional type of booting.

First of all, BIOS checks the availability of boot sector in a device specified in “First (1st) Boot Device” parameter and then in a device “Second (2nd) Boot Device”.

Autodetection of IDE-Devices

First of all, launch the program of auto scanning using a command “IDE HDD AUTO”. This command is located in the main menu of BIOS or directly in a section “Standard CMOS Features”.

To launch auto scanning of IDE-connections, highlight IDE HDD Auto Detection using the arrow keys and press Enter. If there is no such command in “Standard CMOS Features”, return to the main menu pressing Esc. If there is no such command there too, this means that scanning is performed automatically and your capacities are limited.

If auto detection did not help, try again – sometimes BIOS recognizes disks from the second or third attempt. But if this action did not help too, you have to disassemble your system unit. Before doing this, call Customer Services and get all necessary consultations.

You must disconnect your computer and remove its cover. You will see a lot of different wires and cables there. Find the biggest cable – IDE-loop. It may have 40 or 80 wires. Nowadays many producers use “round” IDE-loops: a usual loop but split into parts and hidden into a sleeve.

Each device connected to IDE-cable can be set as Master or Slave. If a similar value was set for both devices located on one cable, this may cause a failure during scanning of system devices and your device will not be recognized. To solve this problem, reinstall a jumper at the back panel of one of devices in the appropriate position. For example, if both devices are connected as Master, reinstall a jumper of one of devices in the position “Slave” or “Cable Select” and leave a jumper of the second device in its initial position.

Having replaced a type of connection, you must check the secure attachment of the power- and IDE-cable to a motherboard or a device. Then switch your computer, enter BIOS Setup Window and try scanning again. If all the steps have been completed properly, the records of all available IDE-devices will appear in “Standard CMOS Features”.

Detection of Available Media

The information about all media – HDD, FDD and CD/DVD-ROM – is stored in a section “Standard CMOS Features” which is also called “Main” or “Standard CMOS Setup”. You can also set the Data and Time in this section.

Select “Standard CMOS Features” from the list of sections and press Enter. The following parameters will occur in a window that opens:

  • System Date;
  • System Time;
  • Primary Master – a leading device on the first IDE-loop;
  • Primary Slave – a slave device on the first IDE-loop;
  • Secondary Master – a leading device on the second IDE-loop;
  • Secondary Slave – a slave device on the second IDE-loop;
  • Floppy Drive A – a main device on FDD-loop;
  • Floppy Drive B – a secondary device on FDD-loop;
  • Boot Sector Virus Protection.

The parameters Primary Master, Primary Slave, Secondary Master and secondary Slave contain a list of devices connected to a motherboard using IDE-loop. The values Primary and secondary identify a slot: a Primary device is connected to IDE-1 Slot and Secondary device is connected to IDE-2 Slot. As a rule, such connection is used for HDD, CD/DVD-ROM and ZIP.

The type of connected device is set in front of each parameter: for example, CD-ROM is for a device of CD reading. The values of main features are set for hard disks – disk type, a number of cylinders, heads, sectors and other.

Key Combination for BIOS Setup Opening

A producer of a computer and motherboard

Key Combination

Acer Ctrl+Alt+Esc
AST, Advantage, Award, Tandon Ctrl+Alt+Esc
Compaq F10
Dell F1 or Del.
Dells Ctrl+Alt+Enter
Gateway F1
Hewlett Packard F1
IBM (outdated models) Rollover of left and right mouse buttons
IBM (models with PS/2) Ins, Ctrl+Alt+?, Ctrl+Ins

(when a pointer is in the left upper corner)

Aptiva F1
Fortiva Ctrl+Alt+A or Ctrl+Alt+S
Packard Bell F1 or F2
Phoenix Ctrl+S, Ctrl+Alt+S, Ctrl+Alt+Ins
Sharp Laptop F2
Sony F3, then F2 or F1
Tandon Esc (directly when the power is turned on) or Ctrl+Shift+Esc
Toshiba Esc, and F1 in older models
Olivetti Shift+Ctrl+Alt+Del on additional keyboard
Miscellaneous Crtl+Esc, Crtl+Alt+ “+”
Zenith Ctrl+Alt+Ins

If everything was done correctly, BIOS Setup window will open, and if something is incorrect, a loading will begin; you can interrupt it by pressing a combination Ctr+Alt+Delete and a key Reset on a system unit.


If you work in DOS, you can open BIOS Setup without the preliminary computer restarting. You should only press one of the following key combinations: Ctrl+Alt+Esc, Ctrl+Alt+Enter, Ctrl+Alt+A or Ctrl+Alt+S. This method is correct for most of computers and cannot be performed in other operating systems, for example Windows, Linux and other. Such key combination cannot also be used in DOS emulator.

As a rule, BIOS SETUP window is a menu with a list of sections that include commands for parameter control. Some BIOS support operation with a mouse and look like a set of files with stored commands.

Computer Loading

The process of computer startup has two clearly expressed options: a computer starts up or it does not load for any reason.

So, there are multiple reasons why you computer does not load: ranging from the absence of power supply to the failure of vital components of the computer, for example a processor.

BIOS Menu Window

BIOS menu window is also called BIOS Setup and you can open it only at the beginning of computer loading during its self testing. In most cases, use the key Delete to open BIOS Setup, but in some cases you can use the other buttons, for example F1, F2 and other. The name of necessary key is written in “Press Del to Enter Setup” or “Hit F2 to Enter Setup” that occurs immediately after the memory testing. Sometimes you can also meet the following message: “Del: Setup”.


LCD monitors have got some delay between computer loading and displaying of transmitted information. That’s why, if a monitor was switched on only after a computer, you may miss these messages. But as BIOS does not depend on monitor, you can press and hold Delete (or F1, F2 and other) and then BIOS Setup will be opened.

The Producers of BIOS

There are two producers of BIOS today: Phoenix and American Megatrends. The first company produces BIOS under the trademarks “AWARD” and “PHOENIX”, the second company produces “AMIBIOS”. You can also find BIOS produced by MR. BIOS Company. Some large producers of motherboards and other equipment, for example Intel and Aser, also produce their BIOS. As a rule, such BIOS can be used only with particular models of motherboards of this manufacturer.

Of course, different Trademarks of BIOS have a lot of differences, despite of similar tasks facing them. First of all, this is directly linked to the possibility of manual setting. For example, BIOS PHOENIX – it has poor possibilities for setting. As a rule, such BIOS is used in multi-processor systems, workstations and some motherboards produced by Intel.

AMIBIOS is wide-spread among outdated computers and soma new ones with low-cost motherboards.

As any other popular software product, BIOS has got several versions. As the capacity of motherboards increases, there is a growing need for increasing the capacities of BIOS. Besides, as any other software, micro-programs for BIOS are constantly updated so as to optimize and expand the initial parameters. It does not mean that you have to update BIOS every week. As a rule, a computer operates well with the pre-installed software.