[Bus Speed FAQ] Difference of Speeds...[Lower or Upper Versions]

[shinigami97yash]

I have in my laptop {Compaq Presario C700} a bus speed of PC2-5300s then can u please tell tell me that bus speed of it's lower version ram will work or not.. {i.e. Like pc2-2300.... bla bla don't know any version }

 

[Rookie_MIB]

What you need for RAM to be compatible:

1) Must be the same DDR type. You cannot mix DDR, DDR2, DDR3 and in your case, I believe it must all be DDR2.
2) The new RAM must be rated faster than or equal to the max bus speed, unless you can adjust your speed on your mainboard down. In a laptop, that is usually not possible since they tend to be more locked down.
3) The RAM modules can always run -slower- than their max rated speed.

So - in your particular case, you have PC2-5300, which means you have a 667mhz bus speed. That means your choices are limited to DDR2-5300 (equal to your current speed of 667mhz), DDR2-PC6400 (800mhz bus speed which will clock down to your 667mhz bus speed), or PC2-8500 (bus speed of 1033mhz).

Those are all DDR2 models, and in general you will not be able to go any slower than PC2-5300 when you pick your new RAM models for the laptop.

 

[shinigami97yash]

so i can buy RAM of PC-6400 too....

 

[Rookie_MIB]

so i can buy RAM of PC-6400 too....

Yes, should not be a problem.