Installing and Troubleshooting CPUs
This section delves into the hands-on steps involved when installing or troubleshooting a CPU. Installation of CPUs has actually become easier over time, especially with the advent of LGA sockets. However, troubleshooting a CPU can be just as much of a challenge as ever. It's important to note that proper installation of a CPU can reduce the amount of CPU failures and the ensuing amount of CPU troubleshooting.
As with most computer components, installing a CPU is easy. But you must be careful, it can be easily damaged. Take it slow, and employ proper safety measures. We break it down into some simple steps:
Select a CPU: If you build a new computer, the CPU needs to be compatible with the motherboard for the type of CPU, speed, socket type, and voltage. If you upgrade a CPU, be sure that it is on the manufacturer's compatible list (which can be found on its website). This might be the motherboard manufacturer, or it could be a proprietary computer manufacturer (such as HP or Dell).Power down the PC, disconnect the power cable (or turn off the kill switch), open the PC, and get your boxes of components ready!
Employ ESD prevention methods: Use an antistatic strap and mat. Remove the CPU and heat sink from the package and place them on an antistatic bag. (One usually comes with the motherboard, but you should have extra ones handy.) Make sure that the CPU's lands (or pins) are facing up to avoid damage. Never touch the lands or pins of a CPU. Before touching any components, place both hands on an unpainted portion of the case chassis. For more information on ESD preventative measures, see Chapter 16, "Safety and Professionalism."
Ready the motherboard: Some technicians prefer to install the CPU into the motherboard and then install the motherboard into the case. If so, place the motherboard on the antistatic mat. (The mat should be on a hard flat surface.) If you install the CPU directly into an already installed motherboard, clear away any cables or other equipment that might get in the way or could possibly damage the CPU, heat sink, or fan.
Install the CPU: Be careful with the CPU! It is extremely delicate! Always touch the case chassis before picking up the CPU. Hold it by the edges (the way you would properly hold a CD) and do not touch any pins, lands, or other circuitry on the CPU. If you need to put it down, put it down on an antistatic mat with the pins/lands facing up. Most of the time a CPU will be installed to either an LGA socket or a PGA socket. The following two bullets show how to install a CPU into each type of socket.
If you install to an LGA socket, unlock the socket by releasing the retaining arm and swinging it open as far as it can go. Open the socket hatch, unhook it if necessary, and remove any plastic cover. Next, place the CPU into the socket. One corner of the CPU has an arrow that should be oriented with the socket's missing pin(s); both of these corresponding corners indicate pin 1, as shown in Figure 3.2. Carefully place the CPU into the socket. The lands on the CPU match up with the lands on the socket if it is oriented correctly. Make sure it is flush and flat within the socket. Close the cap, and secure the retaining arm underneath the tab that is connected to the socket, thus securing the CPU. Next, install the heat sink/fan assembly. On LGA sockets these usually have four plastic snap-in anchors. Carefully press each of these into and through the corresponding motherboard holes. Don't use too much force! Then turn each of them one quarter turn to lock the heat sink in place. Make sure that the heat sink is installed flush with the CPU by inspecting the assembly from the side. You want to be positive of this before turning on the computer because the thermal compound will begin to expand and fill the imperfections right away. Plug the fan into the appropriate motherboard power connector, as shown in Figure 3.3. (These are usually labeled directly on the motherboard, or see your motherboard documentation for details on where to plug in the fan.)
Figure 3.2 Orientation markings on the Q8400 CPU and LGA775 socket
Figure 3.3 An installed multi-core CPU with connected fan
Install the entire motherboard assembly into the case if that is your method of choice.
- If you install to a PGA socket, unlock the socket by moving the retaining arm out and upward until it is at a 90-degree angle to the motherboard. Then gently place the CPU into the ZIF socket. There will be an arrow on one corner of the CPU that should correspond to a missing pin (or arrow) on the socket. Don't use force; slide the CPU around until it slips into the socket. Look at the CPU from the side and make sure it is flush with the socket. Lock down the retaining arm to keep the CPU in place. Then attach the heat sink/fan assembly to the metal clips that are on the sides of the socket. Make sure that the heat sink is installed flush with the CPU by inspecting the assembly from the side. You want to be positive of this before turning on the computer because the thermal compound will begin to expand and fill the imperfections right away. Attach the power cable for the fan to the motherboard. (See your motherboard documentation for details on where to plug the fan in.)
Test the installation: With the case still open, boot the computer to make sure that the BIOS POST recognizes the CPU as the right type and speed. Halt the POST if necessary to read the details, and when done, enter the BIOS and view the CPU information there as well. If the BIOS doesn't recognize the CPU properly, check if a BIOS upgrade is necessary for the motherboard. Also make sure that the CPU fan is functional. Then view the details of the CPU within the BIOS. Be sure that the voltage reported by the BIOS is within tolerance. Then access the operating system (after it is installed) and make sure it boots correctly. Complete several full cycles and warm boots. Finally, view the CPU(s) within Windows and with CPU-Z:
Within Windows: Check in the Device Manager to make sure that the CPU is identified correctly. Navigate to Start and right-click on Computer (My Computer in XP); then select Manage from the drop-down menu. This brings up the Computer Management window. From here locate the Device Manager in the left window pane and click it. Now, from the list in the right window pane, there should be a category named Processors; click the plus sign to expand it, and the CPU you installed should be listed. In Figure 3.4 you can see a different system I am running that has a Core 2 Duo; the CPU shows up as two separate CPUs running at 2.5GHz. You can view similar information in Windows at the System Information window, which can be accessed by pressing Windows+R to open the Run prompt and typing
(in Vista) or
Figure 3.4 A Core 2 Duo CPU as shown in the Device Manager
With CPU-Z: The CPU-Z program can be downloaded from http://www.cpuid.com/cpuz.php; it is freeware that gathers all the information we just saw in the Device Manager and also identifies the voltage, clock speeds, cache memory, and much more. This is the program to use when analyzing and monitoring your CPU, as shown in Figure 3.5. When installed (which is easy), simply run it to analyze your CPU.
Figure 3.5 CPU-Z showing the same Core 2 Duo CPU
- Within Windows: Check in the Device Manager to make sure that the CPU is identified correctly. Navigate to Start and right-click on Computer (My Computer in XP); then select Manage from the drop-down menu. This brings up the Computer Management window. From here locate the Device Manager in the left window pane and click it. Now, from the list in the right window pane, there should be a category named Processors; click the plus sign to expand it, and the CPU you installed should be listed. In Figure 3.4 you can see a different system I am running that has a Core 2 Duo; the CPU shows up as two separate CPUs running at 2.5GHz. You can view similar information in Windows at the System Information window, which can be accessed by pressing Windows+R to open the Run prompt and typing msinfo32 (in Vista) or winmsd (in XP).
The most common issue with a CPU is when it isn't installed properly or securely. This could possibly cause a complete failure when trying to turn the system on. If this happens, always check the power first, just in case. Another possibility is that the system will turn on, and power will be supplied to the system, but nothing else will happen: no POST, no display, no hard drive activity. In either of these situations, after checking power, make sure of the following:
- Check the Big Four: Remember that the CPU is part of the big four including the video card, RAM, and motherboard. Be sure to check these other components for simple connectivity problems, which could be the real culprit and not the CPU at all. In fact, always check connections first before taking the CPU assembly apart.
- Fan is connected and functional: Some motherboards have a safeguard that disables booting if the fan is defective or not plugged in. Or you might get a message on the screen or other type warning depending on the motherboard. Be sure that the fan is plugged into the correct power connector on the motherboard (or elsewhere), and verify that it turns when the computer is on. If the fan has failed, replacement fans can be purchased; just make sure that the new fan is compatible with the heat sink and motherboard.
- Heat sink is connected properly: Make sure that the heat sink is flush with the CPU cap and that it is securely fastened to the motherboard (or socket housing).
- CPU is installed properly: Make sure it was installed flush into the socket and that it was oriented correctly. Of course, this means removing the heat sink. If you do so, you should clean off excess thermal compound and reapply thermal compound to the CPU cap before reinstalling the heat sink.
Here are a few more possible symptoms of a failing CPU:
- Unexplained crashes during boot up or during use.
- The computer locks after only a short time of use.
- Voltage is near, at, or above the top end of the allowable range.
Sometimes, the CPU is just plain defective. It could have been received this way, or maybe it overheated. Perhaps there was a surge that damaged it, or maybe someone overclocked it too far, and it was the victim of overvoltage (and subsequent overheating). Regardless of these reasons, the CPU needs to be replaced. Now, by default CPUs come with a heat sink and fan, and if that is the case, install the CPU as you normally would. But in some cases, you can save money by purchasing the CPU only and use the existing heat sink. In this case, remember to clean excess thermal compound and then reapply thermal compound; but reapply to the CPU cap, not to the heat sink. If the CPU was installed properly, users don't usually have many problems with it (aside from the overclockers). Keep this in mind when troubleshooting the CPU, or when troubleshooting an issue that might appear to be a CPU issue but is actually something else altogether.
Answer these questions. The answers follow the last question. If you cannot answer these questions correctly, consider reading this section again until you can.
You are troubleshooting a CPU and have already cut power, disconnected the power cable, opened the case, and put on your antistatic strap. What should you do next?
Check the BIOS.
Remove the CPU.
Test the motherboard with a multimeter.
You have installed the CPU and heat sink/fan assembly. What should you do next?
Apply thermal compound.
Boot the computer.
Plug in the fan.
Replace the BIOS jumper shunt.
What is a possible symptom of a failing CPU?
CPU is beyond the recommended voltage range.
Computer won't boot.
BIOS reports low temperatures within the case.
Spyware is installed into the browser.
When deciding on a CPU for use with a specific motherboard, what does it need to be compatible with?
Cram Quiz Answers
B. Check connections first; it is quick, easy, and a common culprit.
C. After installing the heat sink/fan assembly, plug in the fan to the appropriate connector on the motherboard.
A. If the CPU is running beyond the recommended voltage range for extended periods of time, it can be a sign of a failing CPU. If the computer won't boot at all, another problem might have occurred, or the CPU might have already failed. Low case temperatures are a good thing (if they aren't below freezing!) and spyware is unrelated, but we talk about it plenty in Chapter 15, "Security."
B. The CPU needs to be compatible with the socket of the motherboard. The case doesn't actually make much of a difference when it comes to the CPU. (Just make sure it's large enough!) There is no wattage range, but you should be concerned with the voltage range of the CPU, and PCI slots don't actually play into this at all because there is no direct connectivity between the two.