Rams and FSB question

[thomas1028]

My cpu FSB is 800 mhz. I have 2 gb of ddr2 667mhz and 1 gb of ddr2 533mhz so 3 gb total. When I look at my Rams in the BIOS, it says the speed is 533mhz but not 667. What is my Rams really running at? And is it true that I'm supposed to try to match the Ram speed with my cpu FSB for best performance?

 

[1Bowtie]

Ram will run at the slowest clocked ram, that's what your seeing. The answer to your second question is yes, if you will go to Crucial.com they have a ram check that will garruntee the proper ram for your comp

 

[Dwarf]

As mentioned above, the speed of your memory bus is governed by the slowest RAM installed. Thus if you have 2 @ 667MHz and 1 @ 533MHz, the bus will run at 533MHz because that is the speed of the slowest RAM. For best performance, you should firstly ensure that all RAM modules are identical (speed, timings, etc). It is better to use the same manufacturer and part number for all sticks. Ideally, your memory speed should match the FSB,but in many cases it does not. In these circumstances, a FSB/RAM divider is used. You FSB is 800MHz, so you will be better off using RAM modules rated at 800MHz (DDR2-800).

 

[thomas1028]

Alright thanks guys! Thats what I was thinking too. But I've just recently got 3 sticks of 800 mhz and the BIOS still show up as 533 lol I see a slight speed increase but nothing too noticeable. What's with the BIOS showing 533 mhz though?

Edit: There are no 533 mhz sticks installed, only 800 mhz sticks

 

[Digerati]

Just to clear something up, the FSB - or front side bus speed is established by your motherboard, not the CPU. If the CPU is not capable of the maximum FSB speed the motherboard supports, the motherboard (chipset) may toggle down the speed to support that CPU.

 

[thomas1028]

So that means my Rams aren't running as fast as they should be?

 

[Digerati]

Your RAM (not Rams) is fully capable of running slower than its rated speed. So "should be" is not really the right term either. Your motherboard, CPU and RAM (random access memory) all must work together. Since we don't know what motherboard or CPU you have, we don't know which one is the limiting factor.

 

[thomas1028]

I just like to call it "Rams" lol anyway I checked the specs and it turns out the mobo only supports 533 mhz. I don't know why they would put a CPU with an FSB of 800 mhz with a mobo that only supports up to 533 mhz...

 

[Digerati]

Perhaps they got a good price.