lenovo u350

now radio soldier

i have a lenovo u350 and its been working properly until yesterday,it says it cant find hard drive when booting up,now,i can boot it from external drive,what could this be.

mp22

New hard drive required.

dyer

enter your bios and make sure your drive is detected and the boot order is set correctly. if the drive is not listed there, power down and check the cables are inserted properly and try again.

now radio soldier

Okay,checked bios,checked connections,and ive put new drive in,still nothing,im confused now

themonic

Problem is with bridge on your mainboard.

_AVALANCHE_

themonic wrote: »

Problem is with bridge on your mainboard.

Is that fixable or is it easier to just get new board??

Robbed from PC Building and Upgrading 101

Knowing what's written here isn't strictly speaking necessary to "build" a computer but knowledge of how the different parts of a computer interact with each other not only gives you a finer appreciation of the inner workings of a computer but is useful in troubleshooting complex hardware issues.

A few basic terms

• I/O = Input/Output. These are devices that are not part of the computer itself but input instructions in to it and output what the computer processes. E.g. in a game, your input would be mouse and keyboard movement and the output would be what is displayed on your monitor.
• Volatile / Non Volatile flash storage = "Volatile" flash storage such as RAM loses its contents every time the computer restarts. Non-volatile flash storage such as an SSD or even a USB stick or SD Card retain their contents even if they're not actively receiving any power.
• RAM = Random Access Memory. Very fast storage that stores instructions for the CPU to process.
• ROM = Read only memory. Fast but usually small storage that's used to store pieces of software that does not change often such as the BIOS (To be explained later) or the firmware of certain devices such as a HDD. Contrary to what the name would imply, it's usually possible to alter the contents of ROMs.
• Cache = Found in many components from the CPU to hard drives. All that a cache does is act as a buffer between two components to compensate for differences in speed. An easy way to understand the purpose of a cache is through example. Take a hard drive for example. I can send commands to a HDD far faster than the HDD can actually perform them. To prevent the computer from having to wait for the HDD to finish the command, it sends the command to the cache to add to a queue of commands.

Motherboard:
As the name would suggest, this is the board which essentially forms the "computer" as a unit. It connects all the components together, transfers instructions and information between them and regulates many aspects of the computer such as voltages and frequencies.

Essentially, the main parts of a modern desktop motherboard and their functions are:

1. Northbridge:
   Connects the main components of the computer used for processing instructions. Namely the CPU, RAM and the video controller. In the past, this may have meant "Integrated Graphics" where the chipset used to process graphics was physically located within the Northbridge. Nowadays, Integrated Graphics tends to be physically located on the CPU. In most Desktops however, a dedicated graphics card is used and connects to the Northbridge through a PCI-Express interface. As you'd imagine the Northbridge needs to be able to communicate information in a synchronised manner and at high speed. The Northbridge then connects to the Southbridge. Very recently, component makers such as Intel have started to put the Northbridge on the same chip as the CPU.
2. Southbridge:
   Communicates with and connects the (Relatively speaking) slower components and inputs/outputs of the computer. Traditionally communicated with the rest of the computer through the Northbridge but that is changing. Examples of components that the Southbridge handles are the system clock, the system management bus (SMBus) which monitors temperatures and adjust voltages to reduce the temperature or increase performance, storage such as hard drives or DVD drives, non-volatile BIOS memory and Audio controller. It also controls many other parts of a computer but they're far too technical for just needing to know how to build a computer. These are things like the interrupt controller that while incredibly important aren't very relevant to someone who just wants to build their own computer.
3. CPU Socket:
   In the past, an actual socket where the CPU's pins used to make connections. Nowadays, with BGA/LGA (Ball Grid Array/Land Grid Array) CPU packages the pins are in the socket and the CPU's pads just rests on the pins. Essentially all that the CPU socket does is provide an interface and power for the CPU. Connects to Northbridge.
4. RAM Sockets:
   Provides power and an interface for the RAM. Connects to Northbridge.
5. ATX Power connector:
   Biggest power cable in the computer. Supplies power to the CPU, Motherboard and RAM as well as the graphics card (Most require another power cable).
6. PWM Fan connectors:
   Provides power to the computer's fans (Whether Chassis or CPU fan) and monitors fan speeds in accordance with component temperatures. Communicates through the SMBus (Southbridge).
7. PCI-Express Slot:
   PCIEx16 slots provide an interface and connect a dedicated graphics card to the rest of the computer through the Northbridge. This provides a very high bandwidth (High Capacity and Speed) link between the slot and the rest of the computer. PCIEx1 slots also provide an interface but they are generally used for expansion cards such as video grabbers and extra USB ports and the like.
8. PCI Slot:
   Slowly being phased out by PCIEx1 slots. Used for the same purpose.
9. SATA/IDE socket:
   Most modern disk drives and DVD/Blu Ray drives are SATA. Older devices are IDE. SATA provides a relatively fast link with the rest of the computer through the Southbridge. Only very high speed SSD drives (Read more on these later) even approach the capacity of SATA. Your standard HDD or DVDRW won't.
10. I/O Panel
    The back panel of most computers. It's where you'll find audio ports, USB ports, a serial port, Legacy keyboard/mouse ports and an Ethernet port or two. A monitor connection may also be available if you have a motherboard or CPU with integrated graphics. Most of these connections are routed through the southbridge to the rest of the computer. That said, there are many controllers in between the port and the southbridge. One example is an ethernet port. The way it would go is Ethernet port -> Ethernet Controller -> Southbridge -> Rest of computer
11. BIOS
    The Basic Input/Output System or "System ROM" is the firmware of the motherboard. By that I mean it is the lowest-level or most fundamental piece of software needed for the computer to even function. It controls many aspects of the computer and may allow the user to configure some settings. Enthusiast motherboards often used for overclocking (Running CPUs at a frequency higher than what the manufacturer intended for better performance) give you control over more or less every aspect of the computer. You can change frequencies, RAM timings and the voltage being sent to the various components of the computer. Another very important function of the BIOS is that it directs the computer to the storage device containing an operating system (The hard drive where Windows is installed in other words). This can be changed to other devices such as a DVD drive or USB stick. It is stored on non-volatile ROM (I.e. it's backed up by a battery that stops it from being erased every time the computer is turned off and not receiving power). It controls the rest of the computer through the Southbridge.
    
    All of these components (And many others that I didn't mention) work together to function as the backbone of a computer.
    
    Here is a diagram of a typical motherboard followed by a schematic of how it all fits together.
    

CPU (Central Processing Unit):
As other have said, the CPU is more or less the brain of the computer. It does the vast majority of the processing required for the computer to function and do work (Except while gaming or working with graphics heavy work such as CAD or Animation). CPUs are incredibly complex chips. They consist of millions of tiny transistors etched on to a silicon die. It's best to describe the CPU through example. I'll use the very popular i5-2500K (Currently powering the computer i'm typing this on).


What you see above this text is a photo of a processor. Normally, the processor is covered by a metal case that's further covered by a metal heatsink and fan but this is what it looks like underneath all of that and at high magnification. As you can see it consists of multiple different parts each composed of millions of transistors.

• Cache:
  There are generally three levels of cache. L1, L2, L3. L1 is the fastest but smallest cache. L2 is average on both counts and L3 is the largest but slowest cache. When I talk of speed here i'm talking in relative terms. CPU cache is incredibly fast. All that the cache does is act as a last site of storage for instructions for the CPU to execute. The typical flow of instructions for say... opening and playing an MP3 would be
  Hard Drive -> RAM -> L3 -> L2 -> L1 -> CPU
  As you can imagine, the more L2/L3 cache you have the less time your CPU will spend idling waiting for instructions and therefore the faster your computer will be.
• Core:
  As this is a photo of a Quad core CPU there are four identical cores. A core itself consists of many different parts each tasked with a different function. Two typical parts (Out of many) are the arithmetic logic unit (ALU) and the control unit (CU). The ALU does what the name would suggest, arithmetic and logic operations and the CU is tasked with taking instructions out of the RAM, converting it and sending it for execution by the ALU and the other units of a CPU. Cores operate at a specific frequency (Measured in GHz) and at a specific voltage (Called the vcore).

themonic

Maybe not easier but cheaper is to replace southbridge than mainboard.