Hardware Reference
In-Depth Information
Be sure to carefully weigh your future needs for computing speed and a multitasking OS
against the amount of money you spend to upgrade current equipment.
Todetermineatwhatpointyoushouldaddmemory,youcanusethePerformanceMonitor
(Perfmon.msc) built into Windows. You can launch it from the Start, Run dialog box or
fromacommandprompt.Tocheckmemoryusage,selectMemoryasthePerformanceob-
ject and enable the following counters:
•
Pages/Sec
—This counter measures the number of times per second that the system
uses virtual (swapfile) memory rather than physical memory. A value above 20 indic-
ates a potential problem. Check the virtual memory settings; if the counter remains
above 20, and it is not during periods of heavy disk or file access, you should consider
installing more memory.
•
Committed Bytes and Available Bytes
—Committed Bytes tracks virtual memory in
use; Available Bytes tracks physical memory available. Add more memory if you run
short of available bytes.
•
Cache Bytes
—Measures the amount of RAM used for file system cache. Add more
RAM if this amount drops below 4MB.
Tip
It is normal to see high Pages/sec counts during periods of heavy disk or file access, such as
when you're running a malware scan, indexing operation, or defragmentation. If the Avail-
able Bytes value doesn't decrease as the Pages/sec value increases, the high Pages/sec num-
bers are probably due to application-generated disk access and not indicative of any sort of
insufficient memory problem or even a bottleneck in memory.
Before you add RAM to a system (or replace defective RAM chips), you must determine
the memory modules required for your system. Your system documentation has this in-
formation.
If you need to replace a defective memory module or add more memory to your system,
you have several methods for determining the correct module for your system:
• Inspect the modules installed in your system. Each module has markings that indicate
itscapacityandspeed.RAMcapacityandspeedwerediscussedindetailearlierinthis
chapter. You can write down the markings on the memory module and use them to de-
termine the type of memory you need. Check with a local store or an online memory
vendor for help.
• Look up your system using the online memory-configuration utility provided by your
preferred memory vendor. Originally, these configuration utilities were primarily for
users of name-brand systems. However, most vendors have now added major mother-
