pc2700 ddr333 running at pc2100 ddr265 speeds

[seasea]

Hello,

I did memtest86 and found that my ram was running at 132mHz (ddr265) speeds. I went into bios and saw that my asus mb config has "memory frequency: AUTO". In the bios description of "auto" it says that by having it autodetect (which sets it at 132mHz (ddr265)), it is being set for the "best performence." I changed it to manually dectect the speed at 166mHz (ddr333) but then the cas when from 2 (at ddr265) to 2.5T and active precharge delay increased by a cycle. Should i keep it at this speed (166 mhz, DDR 333, pc 2700) or go with what my mb believes is the "best performence"

my external clock is running at 133mHz, so should i drop the ram back to 132mHz (ddr265)?

thanks in advance

i think i figured it out. I think i will just have to keep my ddr speed in a 1:1 ratio with my fsb at 133 mHz. So I am guessing the max speed of my cpu fsb is dependent on my ddr speed and likewise my fsb is dependent on my ddr speed?
is this right?

 

[Peter]

You need to tell us what CPU and mainboard you're using. The "1:1 is best" rule doesn't always apply.

 

[seasea]

A7N8X Deluxe (nforce2, socket A, 400 fsb support) with a athlon xp 1800+ (1.5 ghz = 11.5 x 133mHz) (00000681 00000000 00000000 0383FBFF )

A7N8X Deluxe

 

[akira34]

Most likely, it's put the memory to DDR266 because your processor FSB is 133 (or 266)... IF your processor had a FSB of 333 or 400, then the memory would be DDR333 (PC2700)...

 

[seasea]

cool thanx akira

 

[akira34]

NP... You usually find these things out the hard way, or by installing the memory and wondering why it's not as fast as it's supposed to be.

Sort of like how if I have three DDR400 sticks installed on my mobo, they get clocked down to DDR333... Because of that, I'm running just a pair of DDR400 sticks...

 

[LTC8K6]

You can actually run them out of synch if you want. You can see if running the ram faster helps out any with benchmarks.

I have a 533(133) bus P4 with it's memory running at 667(166). 4:5 ratio.

 

[Peter]

Yes, most of the later socket-A chipsets can run the RAM and CPU busses at arbitrary speeds. There is a latency penalty when they're not at the same frequency though. So running faster-specification RAM at the slower, CPU-synchronized speed, possibly with timings set to more aggressive values (which the faster RAM will probably handle OK), is the better choice. No-one will miss the extra bandwidth, and you get the best latency. Note that the opposite is true for systems with integrated shared-memory graphics. In that case, bandwidth is everything, and you go for maximum RAM frequency there.