Upgrading Memory in your HP Pavilion PC
In This Chapter
Learning about memory
How much memory do you need?
Find out what kind of memory your system needs
Purchase and install memory
Project: Verify your Memory Type
Expanding the memory in your system is probably the best way for you to gain a big performance advantage and get rid of the frustration that develops from working on a slow computer. This chapter leads you through the steps of evaluating your current memory configuration and upgrading it to a level that is best for your operating system and the program you use.
This chapter might look a little scary with all the numbers (32 MB, 64 MB, 128 MB, 256 MB) and acronyms (RAM, DRAM, SIMM, DIMM, RIMM, etc.). Don't worry. They look complex only on paper. Upgrading memory is actually a very simple thing. I hate to say it's as easy as changing a light bulb, but that is just about how easy it is. The hardest thing about the project presented here is opening the case and fighting your way through the jungle of wires and cables.
If your Pavilion is still in warranty, keep in mind that you could void your warranty by installing non-Hewlett-Packard authorized parts. Read through this chapter to find out the upgrade potential of your system, then check with your HP service center to find out about performing the upgrade in a way that will not void your warranty. You may need to have HP technicians perform the upgrade using HP-authorized parts.
Chapter 2, "PC Overview for the Uninitiated," introduced basic memory concepts. In that chapter, you learned about how information moves from disk to RAM and then into high-speed memory areas called level 1 and level 2 caches. These caches are like staging areas where information that the computer will need right away is placed. RAM memory is the next best thing. It is not as fast as the cache memory areas, but it's the place where all the documents you are working on are placed until you save them back to disk.
RAM memory is a volatile storage area, meaning that the contents of RAM are lost when the power is shut down.
The more RAM you have, the more programs and documents you can have open. Windows itself loads into RAM when your system starts. Each new version of Windows has become more complex and requires more memory than the previous version. Windows XP now requires a minimum of 256 MB of RAM to operate efficiently. While you can run Windows with less memory, your programs and documents may not have much room. You might be able to run only one or two programs at a time. Performance may drop if you load additional programs.
Virtual memory is a technique used by Windows to ensure that it will run in low-memory conditions. Virtual memory is space on a hard drive that acts like RAM memory, although access speeds are quite a bit lower. When RAM memory runs low, virtual memory is used. The contents of RAM are swapped to and from the virtual memory area on the disk. This will cause a lot of disk swapping, and the hard disk light will flicker continuously. If the system slows to a crawl, shut down some program. You might even consider rebooting. Then consider upgrading your system with more memory.
About the CPU Bus (Front Side Bus)
I've talked about the CPU bus before, but I'll make some important points here again. First, the CPU bus is also called the front side bus. It is the pathway between the CPU and memory (and also AGP video on some motherboards) over which data is transferred. Figure 2.8 in Chapter 2 illustrates the architecture of the bus in relation to other motherboard components.
The CPU bus runs at a specific clock rate and the faster the clock rate, the better the access rate and performance. The clock rate is 66 MHz for older motherboards and 100 MHz or 133 MHz for newer motherboards. You can look ahead to Table 6.1 to find out the clock rate that your motherboard supports. The rate at which this clock runs depends on the CPU in the system. Older Celeron CPUs support a 66 MHz CPU bus, so when you buy memory, you buy memory modules that run at 66 MHz. Pentium III CPUs run at either 100 MHz or 133 MHz, depending on the CPU model and what is allowed by the motherboard. If you have a 100 MHz CPU bus, then you buy 100 MHz memory (called PC100, as explained later). If you have a 133 MHz CPU bus, then you buy 133 MHz memory (called PC133, as explained later). Some systems support double-clock rates, which allows the CPU bus to transfer data to and from memory at twice the normal speed. For these systems, you purchase DDR (double data-rate) memory modules as explained later.
Note that some HP motherboards use Intel 810 or 810e chipsets as described in Appendix A. One of the big differences between these chipsets is that the 810 supports a 100 MHz CPU bus and 100 MHz memory modules while the 810e supports a 133 MHz CPU bus and 133 MHz memory modules.