CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [97]
Figure 6-23 FreeMeter
System RAM Recommendations
Microsoft sets very low the minimum RAM requirements listed for the various Windows operating systems to get the maximum number of users to upgrade or convert, and that’s fine. A Windows XP Professional machine runs well enough on 128 MB of RAM. Just don’t ask it to do any serious computing, such as running Doom III! Windows Vista has raised the bar considerably, especially with the 64-bit version of the operating system. Here are my recommendations for system RAM.
Determining Current RAM Capacity
Before you go get RAM, you obviously need to know how much RAM you currently have in your PC. Every version of Windows works the same way. Just select the Properties for My Computer or Computer to see how much RAM is in your system (Figure 6-24). If you have a newer keyboard, you can access the screen with the WINDOWS-PAUSE/BREAK keystroke combination. Windows 2000, XP, and Vista come with the handy Performance tab under the Task Manager (as shown in Figure 6-25).
Getting the Right RAM
To do the perfect RAM upgrade, determine the optimum capacity of RAM to install and then get the right RAM for the motherboard. Your first two stops toward these goals are the inside of the case and your motherboard manual. Open the case to see how many sticks of RAM you have installed currently and how many free slots you have open. Check the motherboard book to determine the total capacity of RAM the system can handle and what specific technology works with your system. You can’t put DDR2 into a system that can only handle DDR SDRAM, after all, and it won’t do you much good to install a pair of 2-GB DIMMs when your system tops out at 1.5 GB. Figure 6-26 shows the RAM limits for my ASUS Crosshair motherboard.
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NOTE The freeware CPU-Z program tells you the total number of slots on your motherboard, the number of slots used, and the exact type of RAM in each slot—very handy. CPU-Z not only determines the latency of your RAM, but also lists the latency at a variety of motherboard speeds. The CD accompanying this book has a copy of CPU-Z, so check it out.
Mix and Match at Your Peril
All motherboards can handle different capacities of RAM. If you have three slots, you may put a 512-MB stick in one and a 1-GB stick in the other with a high chance of success. To ensure maximum stability in a system, however, shoot for as close as you can get to uniformity of RAM. Choose RAM sticks that match in technology, capacity, and speed. Even on motherboards that offer slots for radically different RAM types, I recommend uniformity.
Figure 6-24 Mike has a lot of RAM!
Mixing Speeds
With so many different DRAM speeds available, you may often find yourself tempted to mix speeds of DRAM in the same system. Although you may get away with mixing speeds on a system, the safest, easiest rule to follow is to use the speed of DRAM specified in the motherboard book, and make sure that every piece of DRAM runs at that speed. In a worst-case scenario, mixing DRAM speeds can cause the system to lock up every few seconds or every few minutes. You might also get some data corruption. Mixing speeds sometimes works fine, but don’t do your income tax on a machine with mixed DRAM speeds until the system has proven to be stable for a few days. The important thing to note here is that you won’t break anything, other than possibly data, by experimenting.
Figure 6-25 Performance tab in Windows XP Task Manager
Okay, I have mentioned enough disclaimers. Modern motherboards provide some flexibility regarding RAM speeds and mixing. First, you can use RAM that is faster than the motherboard specifies. For example, if the system needs PC3200 DDR2 SDRAM, you may put in PC4200 DDR2 SDRAM and it should work fine. Faster DRAM is not going to make the system run any faster, however, so