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Why is my 3200 @ less than 2100???????

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DarkSide8416

Member
Joined
Oct 21, 2002
Location
Houghton, Michigan
Everything in the BIOS is at default and at boot up it says DDR400, yet when I run the SiSandra memory bandwidth benchmark it performs worse than PC2100.
What the heck???????
 
even if you have pc3200 ram, it normally will only run at the rate of your fsb. some motherboards allow the mem freq to be set asynchronous to the fsb freq in the bios, i.e. fsb at 166Mhz, mem at 200Mhz. i don't know if your mobo or bios supports this. however, some benchmarks have shown that running the mem async gives little improvement to the mem bandwidth. in short, run your mem sync and oc your fsb :)
 
Ahhh yes, another case for me to deal with :D

Basically, your memory is running faster than your system can handle. Running your memory really fast, but leaving the fsb at normal speeds on an AMD system is pointless. You have to increase your fsb for the system to have the extra power to use that bandwidth.

For AMD's......Memory MHz should = FSB MHz
 
I get a nice bump in memory bandwidth from my PC3200 when I go from 1:1 to 4:6 but I'm running a P4 at 133mhz.
 
well ive got my FSB at 185 now and my timings at 2-6-2-2 and SiSandra shows my ram barely below PC3200, a ton better than before. Only problem is my AGP doesnt like the FSB above 178 >.<
 
I would like to try to set it at a 4:5 ratio but I cannot find that option in my BIOS. I am using the BIOS with my Abit KD7-S, do I have to flash it?
 
CChaos said:
I get a nice bump in memory bandwidth from my PC3200 when I go from 1:1 to 4:6 but I'm running a P4 at 133mhz.

This is because a P4 has a quadruple rate FSB to the processor while AMD has only a double rate. AMD processors can use the bandwidth provided by DDR running at the same FSB, no more. P4 processors can use twice that.

Dual channel or high ratios with AMD give very small boosts, simply because no memory actually runs at quite its theoretical bandwidth. But the most a processor can use is the full theoretical bandwidth. And often, running asynchronously will decrease performance, due to the difficulty of changing one signal to another.

High ratios and dual channel work wonders for Pentium 4's because they can use the extra bandwidth you give them.

Of course these are both far above a pentium 3, which could only use 1050mb/s, (and thus rarely used anything other than pc133 sdram, with identical theoretical bandwidth.)
 
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