[EJayJay]

Hello all,
This is a wonder why this happens question. My system is a P4 3.06GHz 533MHz FSB on a Jetway P4X400DBP mobo. Just installed two 512MB Crucial Technology PC3200 DIMMs. Now, in BIOS, if "set DRAM clk at next boot" is set to 200MHz, when the computer boots up it will show mem frequency at 400 and DRAM type as 400. However, it caused several system errors during normal usage. Running Memtest86 showed more than 100,000 errors on test #5 after one pass.
So, I backed down "set DRAM clock at next boot" to 166MHz (by SPD). Now when the machine boots up it reads mem frequency as 333 and DRAM type as 400 and when I ran Memtest86 at this setting, I receiced zero errors! Why such a vast discrepency? :4-dontkno I thought the ideal settting was for mem frequency and DRAM type to be the same. I also was under the impression that this mobo, proc, & RAM should ideally operate at the higher setting. :sad:
Also, after receiving all those errors origanally, and before backing down the mem frequency, I contacted Crucial and told them I thought I had a bad DIMM. They exchanged it promptly, to their great credit. Of course the new DIMM did about the same thing before backing off the setting. So, why can't the DRAM clk be set to 200MHz on this system?
I am really curious and thanks for any input you can supply. :smile:

 

[twajetmech]

Your memory and cpu run on a 533mhz bus freq not 800, thus putting in pc3200 (800 mhz) memory will in essense try to overclock your system to an 800 fsb rather than the pc2700 (533mhz) that it should be, causing your instability.

 

[EJayJay]

Who said dat?

What? According to Crucial's website and it's Memory Advisor Tool, the recommended memory for this mobo is 512MB DIMMs of DDR PC3200, which is specifically why I purchased it. You don't reckon they made an error do you and made me buy the wrong memory? :4-thatsba
It does state that I could use PC2100, PC2700, and PC3200 DIMM, but RECOMMENDED the PC3200.

 

[twajetmech]

Your cpu and mobo only has support to pc2700 memory (fsb of 533) You most certainly use pc3200 on the mobo but you will have to underclock it like you are now for stability unless you know what your doing with overclocking, which on your current setup I would not advise. I would susspect that their website was in error, however with pc2700 memory becoming scase more than likely they are simply trying to rid themselves of overstock ddr to make room for the new ddr2, not entirely false advertising but tricky if you don't do this stuff everyday.

 

[EJayJay]

The wanks! :deveous: You're probably right. So if I am clocking now at about 333 that is equivilant to PC2700? Still faster than PC2100 though? :sayyes:
Thanks for the input.

 

[please]

@ EJayJay
The memory you have now is just a bit overspec for your needs, but that is not always a bad thing. You are right about ideally running the FSB and memory at the same frequency, and that is what you are doing now by running both RAM and CPU at 333MHz. You also may have some sort of 'divider' or FSB/MEM ratio' setting in your BIOS where you may be able to run your memory at PC3200 (400MHz memory bus speed) while your CPU is at 333MHz. If you have an option of '2:3' or '333/400' available, that might be what you are looking for. It would be known as running 'asychronous mode' and might not be quite as fast as what you are running now in 'sychronous mode'.

If you find the BIOS settings and can run the memory at PC3200, try a few benchmarks like Everest and PiFast to see what gives you better performance.

 

[EJayJay]

AAAH! Many thanx, please, for the tip. :smile: I will try a couple of tweaks but will probably leave the settings where they are as the machine is running fairly well.