Wrong RAM?

[aidso]

I have just bought a new Shuttle pc and according to Crucial it takes the follwing RAM:

240 pin DIMM, DDR2 PC2-6400

I have the following RAM in the house, salvaged from another machine:

240 pin DIMM, DDR2 PC2-4200.

Will this latter RAM work in my Shuttle? What does the last part of the "model number" mean?
Thanks

[Sputnik]

The 4200 & 6400 refers to the Frequency at which the memory is rated to run at.

4200 = 533Mhz and 6400 = 800Mhz.

If you have the BIOS setting to do it you maybe able to use it. you would have to change the CPU to memory ratio.

[blueball]

It will work but will not be as fast as the 6400 memory. The last number indicates the speed.

[aidso]

ah right. Thanks

stoopid ram

[xirokx]

if you use that RAM it will actually slow the fast stick down...

so even the faster ram stick will run at slower ram stick speed...

[Hyperviper34]

Pc2 – 4200 = 266 Max synchronous FSB
Pc2 – 5300 = 333
Pc2 – 5400 = 338
Pc2 – 6400 = 400
Pc2 – 8500 = 533
Pc2 – 8800 = 550
Pc2 – 9200 = 575
Pc2 – 9600 = 600

the E2160, 2180, 2200 and 5200 etc have a FSB of 200MHz so can run on any of the above memory.

The E7200 or Q6600 has a FSB of 266MHz so will run on all the above

Any 1333MHz CPU like the 8200 has a FSB of 333mhz, so will require a minimum of Pc2 – 5300 and above.

So depending on how high you plan to clock a CPU needs to be taken into account when picking your RAM.

[ed^chigliak]

PC6400 = 800Mhz and it's what I would consider to be the normal speed for DDR2. You also have different timings to consider. CL4 is fast, CL5 is average and CL6 is slow. You can pick up 4GB PC6400 CL4 for as little as £40-£50. I usually look for RAM that will do 4-4-4-12 timings on less than 2.1v as a sign of quality. DDR2 defaults are something like 1.8v and 5-5-5-15 (maybe 18) which is typical for value RAM. With the premium RAM you will need to adjust the bios manually to increase the voltage and tighten the timings.

[blueball]

Under Vista you'll see very little diff between CL types, raw speed makes more impact

[ed^chigliak]

If you have RAM capable of fast timings they will take more speed given less aggressive timings. In fact PC8500 5-5-5-15 and PC6400 4-4-4-12 are probably the exact same stuff with PC6400 generally being the cheaper option. I wish the manufacturers would guarantee a range of operation for the RAM which is how it is in reality.