MaximumPC 2005 10

RAM

R

A

M

TABLE 1: COMMON DDR MEMORY SPEEDS

PC RATING THROUGHPUT DDR RATING (EFFECTIVE

CLOCK SPEED)

ACTUAL CLOCK SPEED

PC1600 1.6GB/s DDR200 100MHz

PC2100 2.1GB/s DDR266 133MHz

PC2700 2.7GB/s DDR333 166MHz

PC3200 3.2GB/s DDR400 200MHz

PC3700 3.7GB/s DDR466 233MHz

PC4000 4.0GB/s DDR500 250MHz

PC4400 4.4GB/s DDR550 275MHz

PC4800 4.8GB/s DDR600 300MHz

PC5600 5.6GB/s DDR700 350MHz

The latest Intel chipsets for the Pentium 4

use DDR2 memory—second-generation DDR

memory. Compared with DDR memory, DDR2

runs at lower voltages to reduce heat, boasts

larger-capacity chips to permit higher memory

capacities per DIMM module, and uses other

design tricks to run at faster clock speeds, as

shown in Table 2. However, as DDR2 memory

speeds increase, their latency also goes up.

Thus, you shouldn’t expect a DDR2 system

running PC2-3200 (DDR2 400) to be much

faster than a comparably equipped system

running PC3200 (DDR400) memory. The

true benefi ts of DDR2’s comparably higher

clock-speeds won’t begin to show up until

motherboards that can accommodate higher

clock speeds start shipping.

TABLE 2: COMMON DDR2 MEMORY SPEEDS

PC RATING THROUGHPUT DDR2 RATING (EFFECTIVE

CLOCK SPEED)

ACTUAL CLOCK SPEED

PC2-3200 3.2GB/s DDR2 400 200MHz

PC2-4300 4.2GB/s DDR2 533 266MHz

PC2-5400 5.6GB/s DDR2 667 333MHz

PC2-6400 6.4GB/s DDR2 800 400MHz

THE COMPLETE GUIDE TO CHOOSING THE RIGHT RAM

Maybe you don’t want to know the details—you just want to fi nd out what kind of RAM you need and get on with your life. Here’s a

handy guide to pairing the correct type of RAM with your motherboard and chipset.

ATHLON XP RAM GUIDE

ATHLON XP MODEL

NUMBER

PROCESSOR

FSB

MEMORY

1500+ 1600+ 1700+ 1800+

1900+ 2000+ 2100+, 2200+,

2400+, 2600+**

266MHz DDR PC2100

2500+ 2600+**

2700+

2800+

3000+***

333MHz DDR PC2700

3000+***

3200+

400MHz FSB DDR PC3200

**Some 2600+ run at 266MHz FSB, while others run at 333MHz FSB.

***Some 3000+ run at 333MHz FSB, while others run at 400MHz FSB.

DDR VS. DDR2: HOW DO THEY COMPARE?

ATHLON 64 AND FX RAM GUIDE

ATHLON 64/FX

SOCKET TYPE

MEMORY

Socket 940 Registered dual-channel DDR PC1600,

PC2100, PC3200*

Socket 939 Dual-channel DDR PC1600, PC2100, PC3200*

Socket 754 Single-channel DDR PC1600, PC2100,

PC3200*

*Memory configurations might differ with CPU due to on-die memory controller.

38 MA XIMUMPC OCTOBER 2005

BUYERS GUIDE

PENTIUM 4 RAM GUIDE

SOCKET TYPE CHIPSET MEMORY

INTEL CHIPSETS

Socket 423 850, 850E Rambus RDRAM

Socket 478 845, 845G, 845GV, 845GL PC-133 SDRAM or DDR PC2100/PC1600*

845GV PC-133 SDRAM or DDR PC2700/2100/1600*

845GE, 845PE DDR PC2700/2100

848P DDR PC3200/2700/2100

865G, 865PE, 865GV Dual-channel DDR PC3200/2700/2100

865P Dual-channel DDR PC2700/2100

875P Dual-channel DDR PC3200/2700/2100

Socket 478, Socket 775 910GL Dual-channel DDR PC3200/2700

Socket 775 915GL Dual-channel DDR PC3200/2700

915GV, 915P, 915G Dual-channel DDR PC3200/2700 or dual-channel

DDR2 PC-4200/3200*

925X, 925XE Dual-channel DDR2 PC-4200/3200

915PL DDR PC3200/2700

955X Dual-channel DDR2 PC2-5300/4200

VIA CHIPSETS

Socket 478 P4X266, P4X266E, P4M266 PC-133/100 SDRAM or DDR PC2100/1600*

ProSavage P4M266 DDR PC2700/2100

P4X400 DDR PC2700/2100/1600

PM800 DDR PC3200/2700/2100

Socket 478, Socket 775 PT880 Pro, PT880 Ultra, PT894, PT894 Pro Dual-channel DDR PC3200/2700/2100 or dual-

channel DDR2 PC-4200/3200*

P4M800 Pro DDR PC3200/2700/2100 or DDR2 PC2-4200/3200*

NVIDIA CHIPSET

Socket 775 nForce4 SLI Intel Edition Dual-channel DDR2 PC2-5300/4200/3200

*Check motherboard to determine which memory type your system supports. You can also use system-analysis programs such as SiSoftware Sandra 2005

Lite (www.sisoftware.co.uk/) to determine this information.