Ram Help!

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s0M30n3

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Ok what i basicly want to know is will ram work to the speed its ment to be if the cpu fsb is lower and will a cpu go as fast as it should if the ram is slower.

I have some people telling me if the ram is faster than the cpu then the ram will slow down to the spped of the cpu and i have some people telling me that they have ram running at 3200 but a cpu of 333 fsb. so can someone help! and if u can run the ram faster than the cpu or the cpu faster than the ram how do i do this?
 
Faster RAM will clock itself down to the CPU's FSB speed. RAM, however, cannot overclock itself to accomodate higher FSB speeds. The CPU's FSB does no adapt itself to anything. Only the RAM does.

As far as DDR goes, Ill highlight the most common ones and their rated compatability front side bus speeds. The higher ones on the list (left) are compatable with the lower ones on the list (right).


PC4000 (266MHz x 2 = (roughly) 533MHz) >> PC3200 (200MHz x 2 = 400MHz) >> PC2700 (167MHz x 2 = (roughly) 333MHz) >> PC2100 (133MHz x 2 = 266MHz)

Note: DDR2 is not compatable with DDR1. Listed above are DDR1 module speeds.
 
just so your not confused... when he says.. the CPU's fsb doesnt adapt itself to anything( but if u were running slower ram then the CPU fsb) it would act as if the CPU was at a lower fsb anyway, cause the ram would bottleneck the bus.

so there is no way around it, u need to match the speed of the ram to the speed of the CPU's fsb, and supported motherbourd bus limit.

example- 333 x 8 = 2664, just round that off to pc2700, and thats the max supported ram speed for that size bus, unless u overclock.
 
RAM, however, cannot overclock itself to accomodate higher FSB speeds.

Well...thats kind of untrue in my case. I have an AMD Athlon XP 2400+ FSB of 266 so of course by default in my BIOS I have it at 15x133 cause multi is locked and I don't care to OC this chip..not on this mobo.

Anyway...I have one stick of PC2700 ram and one stick of PC3200 ram...most people would think that both would be underclocked to meet the standards of PC2100 RAM, but this is not the case....my motherboard is set to BY SPD right now instead of me setting the frequencies to get the 1:1 ratio and it has my ram Overclocked (for the pc2700 anyway) to 2x199=398MHz, so just 2MHz short of the complete 400 PC3200 memory. My computer did that when it was just the PC2700 in there...decided to run it at almost PC3200 speeds and I've had no problems with it regarding instability or anything.

Generally though you want. You can have a slower CPU than the RAM...and have probably an easier time of your motherboard just OC'ing the ram to compensate like mine did......but if You have a fast CPU with 400FSB the RAM will definitely bottleneck it...unless it too can be overclocked to a perfect 2x200 for 400PC3200 ram.
 
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