Ddr333 and ddr400 compatibility issue

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I have a Pentium 4 pc, and I wanted to upgrade its memory.

I have a 512 pc333 already installed.

I occasionally hear beeps and the pc will restart. My friend gave my a pc 400 ddr 1gb.

I’m a bit hesitant in installing these memory module. Will this work?

 or should I remove the pc333 and have the pc 400 all by itself?

Best Answer by JoannaTech
Best Answer
Best Answer
Answered By 0 points N/A #121191

Ddr333 and ddr400 compatibility issue


Don't worry your computer won't be damaged if you try to attach a PC333 DDR1 memory stick to work with a PC400 DDR1. It won't do damage if ever they are not compatible with each other. DDR stands for Double Data Rate.

DDR1 RAM is the old version of memory. When I bought my Kingston 512MB DDR1 memory stick last year, I already saw in the brochure new versions of RAM sticks.

The latest I saw that time was DDR2 and DDR3. You cannot combine both DDR1 with DDR2 or DDR3 sticks because they differ in size physically. DDR1 is quite shorter in length, 184 pins only. Compared to DDR2 DIMMs which is 240 pins. Here’s a list of DDR1 DIMMs (Double In-Line Memory Module):

  1. PC2100 (DDR266)
  2. PC2700 (DDR333)
  3. PC3200 (DDR400)

The numbers beside the DDR refers to the speed of the memory module. PC2100 (DDR266) is no longer carried and is already obsolete. DDR333 and DDR400 are backward compatible to DDR266.

Generally, memory modules are designed to be backward-compatible so there is really no problem if you use these 3 types of memory in-combination on your computer.

But on the other hand, if you combine these memories on your computer, your system will run at the speed of the lowest module or the “lowest common denominator” effect. For example, you use a combination of PC2100 and PC3200 on your computer; it will run at the speed of the PC2100.

But bear in mind that, you cannot mix a DDR with an SDRAM, or a DDR2, or a DDR3. They must be of the same type.

Answered By 0 points N/A #121192

Ddr333 and ddr400 compatibility issue


It will definitely work (unless the DDR400, 1 GB module has problems). When you mix 2 or more DDR SDRAMs with different speeds, the one with the lower speed will be the speed that your system will use. 

So in your case, your memory will run at 333MHz (the speed of your DDR333 module) and so will you front side bus.

You have to make a choice though. If you want your memory and front side bus to run at 400 MHz, you will have to remove the DDR333 memory module. If you prefer having a larger memory at the expense of speed, then you can mix both RAM modules.  Pentium 4 works faster with 400 MHZ front side bus. 

My suggestion is to try both configurations and run benchmarks to see which you like better.

And regarding the beeps before your system restarts, it might not be the memory that's the problem.

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