Ever wonder what memory goes in your computer?
Whenever I go to upgrade I never really know which memory to get.
These are the main things to know.
The rules:
Know how many slots you have and what type of chips they take. (The crucial tool is good for showing that)
These are the current types: (see list at bottom)
SDR (ancient machine – don’t bother upgrade)
DDR (more than a few years old – may be worth the upgrade)
DDR2 (recent machines)
DDR3 (new machines)
Within the type you can generally use the higher numbered models as they are faster and backwards compatible. Also the number of pins and the notch position will physically prevent you from plugging in the wrong type of memory (for the most part).
Most DDR2 and DDR3 chips should be installed in pairs (or trios) to get the best performance – the tools or manufacturer should tell you that.
Finally, how much to add. Well that is a big topic but Windows 32 bit machines can really only use about 3.5G (4G minus the memory on your video card). That is why there is a silent switch to Windows 64 bit in the higher end market and it will become mainstream soon. With 64 bit the limit is 128G or something crazy high like that (crazy for the moment).
Some common systems and what type of memory they have
DDR SDRAM
Dell Dimension 4500S (2 slots) PC2700, PC3200
DDR2 SDRAM
Dell Dimension 9200c or XPS210 (4 slots paired) PC2-5300
Dell OptiPlex 330 (2 slots paired) PC2-5300, PC2-6400, PC2-8500
Dell OptiPlex 360 (2 slots paired) PC2-6400, PC2-8500
Tools
Dell (web)
Tool to scan system and order memory and other parts: Tells you what slots have what chips
http://accessories.us.dell.com/sna/DellPartsFamily.aspx?c=us&cs=04&l=en&s=bsd&~ck=anavml
Crucial (web)
http://www.crucial.com/systemscanner/index.aspx
CPU-Z (app)
http://www.cpuid.com/cpuz.php
General Information
FAQ
http://www.tomshardware.com/forum/55024-30-memory-please-read-posting
http://en.wikipedia.org/wiki/Dimm
Images
http://memoryguide.org/pmwiki.php?n=RAM.DDR
SDR SDRAM (168 pin 2 notches)
DDR SDRAM (184 pin)
DDR2 SDRAM (240 pin)
DDR3 SDRAM (240 pin)
Speeds
For various technologies, there are certain bus and device clock frequencies that are standardized. There is also a decided nomenclature for each of these speeds for each type.
SDR SDRAM DIMMs – These first synchronous registered DRAM DIMMs had the same bus frequency for data, address and control lines.
144 or 168 pin (two notches)
- PC66 = 66 MHz
- PC100 = 100 MHz
- PC133 = 133 MHz
DDR SDRAM (DDR1) SDRAM DIMMs – DIMMs based on Double Data Rate (DDR) DRAM have data but not the strobe at double the rate of the clock. This is achieved by clocking on both the rising and falling edge of the data strobes.
184 pin (single notch)
- PC1600 = 200 MHz data & strobe / 100 MHz clock for address and control
- PC2100 = 266 MHz data & strobe / 133 MHz clock for address and control
- PC2700 = 333 MHz data & strobe / 166 MHz clock for address and control
- PC3200 = 400 MHz data & strobe / 200 MHz clock for address and control
DDR2 SDRAM SDRAM DIMMs – DIMMs based on Double Data Rate 2 (DDR2) DRAM also have data and data strobe frequencies at double the rate of the clock. This is achieved by clocking on both the rising and falling edge of the data strobes. The power consumption and voltage of DDR2 is significantly lower than DDR(1) at the same speed.
200 or 240 pin (single notch)
- PC2-3200 = 400 MHz data & strobe / 200 MHz clock for address and control
- PC2-4200 = 533 MHz data & strobe / 266 MHz clock for address and control
- PC2-5300 = 667 MHz data & strobe / 333 MHz clock for address and control
- PC2-6400 = 800 MHz data & strobe / 400 MHz clock for address and control
- PC2-8000 = 1000 MHz data & strobe / 500 MHz clock for address and control
- PC2-8500 = 1066 MHz data & strobe / 533 MHz clock for address and control
- PC2-9600 = 1200 MHz data & strobe / 600 MHz clock for address and control
DDR3 SDRAM SDRAM DIMMs – DIMMs based on Double Data Rate 3(DDR3) DRAM have data and strobe frequencies at double the rate of the clock. This is achieved by clocking on both the rising and falling edge of the data strobes. The power consumption and voltage of DDR3 is lower than DDR2 of the same speed.
240 pin (single notch)
- PC3-6400 = 800 MHz data & strobe / 400 MHz clock for address and control
- PC3-8500 = 1066 MHz data & strobe / 533 MHz clock for address and control
- PC3-10600 = 1333 MHz data & strobe / 667 MHz clock for address and control
- PC3-12800 = 1600 MHz data & strobe / 800 MHz clock for address and control
- PC3 16000 = 2000 MHz data & strobe / 1000 MHz clock for address and control
