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What is HD RAM? Motherboards that work with HD RAM Troubleshooting Beep Error Codes List of Beepcodes Troubleshooting Dead Newly Assembled Computer Troubleshooting Dead Older Computer Troubleshooting no power CMOS battery problems Windows XP Repair Install If XP Repair Install not possible Error Performing Inpage Operation Guard Against Virus & Malware Attack Top 10 Anti-Spyware Programs
High Density DDR SDRAM Memory - upgrade or low-grade?
In this context High Density memory means the non-ECC 1 GB 184 pin SDRAM PC3200 DDR-400 memory sticks that have become so common on Internet auction sites. The non-ECC bit must be emphasized here because High Density ECC PC3200 server memory is made by a number of perfectly respectable manufacturers and there are no problems with this when used as intended.
How RAM is organised
There's a great deal of misunderstanding about just how SDRAM is organised and what the numbers mean so we'll clear this up before continuing:
PC3200 is DDR SDRAM specified to operate at 200 MHz using DDR-400 chips with a bandwidth of 3,200 GB/s. As DDR stands for Double Data Rate this means that the effective clock rate of PC3200 memory is 400 MHz.
1 GB PC3200 non-ECC sticks are usually made with 16 512 Mb chips, 8 down each side (512 Mb x 16)/8 bits = 1024 Mb. The individual chips making up a 1 GB memory stick are usually organised with 64M bits and a data width of 8 bits, commonly expressed as 64M x 8. Memory manufactured in this way is LOW DENSITY RAM and will usually be OK with any motherboard specifying PC3200 DDR-400 memory.
As the price of Low Density PC3200 DDR RAM has soared, however, an increasing number of people - usually sellers on auction sites - have been offering High Density PC3200 DDR-400 non-ECC RAM for sale at temptingly low prices.
Again in the context of the 1 GB non-ECC PC3200 SDRAM stick there is very little visually to differentiate Low Density from High Density RAM. High Density DDR RAM sticks will, like their Low Density counterparts, usually be double sided with eight 512 Mb chips per side. The difference is that each chip, instead of being organised in a 64M x 8 configuration is organised with 128M bits and a data width of 4 bits, or 128M x 4.
Most High Density PC3200 modules are assembled using Samsung chips. These chips come in both the familiar 22 x 10mm (approx) TSOP2 and smaller squarer 12 x 9mm (approx) FBGA package sizes. High density Samsung chips can be identified by the numbers on each chip. If the sixth and seventh characters are "04" (for example K4H510438D-UCCC) then the chips are x 4 and High Density. If the sixth and seventh characters are "08" then the chips are x 8 and Low Density.
PC3200 High Density module made with Samsung TSOP2 packaged chips
PC3200 High Density module made with Samsung FBGA packaged chips