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Ram running at half speed

By hoodeddeathman
Feb 14, 2008
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  1. hey im running my pc with 2x 1GB patriot 6400 sticks of ram on an Asus p5w dh deluxe mobo and an intel core 2 duo E4500 2.2ghz currently overclocked to 2.6ghz. what i have noticed is that the ram on dual channel is running at 180mhz and on the post bios message i see "dual chanel ram 3200" and if i hitch up my processors clock speed the ram speed falls. whats going on and how can i fix this. all help appreciated thanks.
  2. hoodeddeathman

    hoodeddeathman TS Rookie Topic Starter

    oh and if i mod the ram speed as well as the cpu speed i get a message from the bios "over voltage or overclocking failed"
  3. mailpup

    mailpup TS Special Forces Posts: 8,426   +217

    The BIOS reports 3200 because the RAM is DDR or double data rate, so double 3200 is 6400.
  4. LinkedKube

    LinkedKube TechSpot Project Baby Posts: 4,265   +41


    To me that's still weird isnt it, To me it sounds like his bios is seto to keep cpu:ram to 1:1 maybe, could that be it? I had ddr2 6400, I never got anything like that.
  5. Cinders

    Cinders TechSpot Chancellor Posts: 1,313   +12

    If you didn’t set the ram speed to “limit” or something similar to that in the BIOS then your motherboard will use a divider to underclock your ram while you overclock your processor. You have to make sure the ram divider is locked at "1 to 1" or 200MHz and then raise the front side bus speed if you want to overclock the ram and the processor.

    Your current memory bandwidth is 183X4X8 = PC5856 (really it's bandwidth is calculated with 183X2X2X8). Your actual memory bandwidth should be 200X4X8 = PC6400 or higher with a memory overclock. Your current FSB is actually in the 236-237 range. If you simply set the memory to “Limit” and don’t bother to change the Front Side Bus speed your memory bandwidth will be between 7552 – 7584 and chances are your computer will not boot. GO back into your BIOS and set the memory speed to Limit and your FSB back to 200 and try overclocking again. Your current memory may not allow you to overclock your processor to 2.6GHz if you synchronize the FSB and memory speed, but DDR2 PC8500 is cheap and will have more than enough headroom to overclock your processor.

    http://www.newegg.com/Product/Product.aspx?Item=N82E16820231144
  6. mailpup

    mailpup TS Special Forces Posts: 8,426   +217

    @ Super. Actually, I think I usually see the BIOS reporting MHz as in 400Mhz which doubled is 800MHz instead of 3200/6400. I'll have to look again later as at the moment I am not on a PC that has DDR RAM.
  7. Cinders

    Cinders TechSpot Chancellor Posts: 1,313   +12

    Yes DDR memory speed is usually reported at twice its' actual clock speed. So DDR1 or DDR2 memory that actually runs at 200MHz is reported at DDR speeds or twice the memory clock speed or 400MHz. DDR1 is effectively double-pumped while DDR2 is effectively quad-pumped.

    http://en.wikipedia.org/wiki/DDR2_SDRAM
  8. hoodeddeathman

    hoodeddeathman TS Rookie Topic Starter

    Fixed

    thanks for your help and sorry i took so long to reply. by fine tweaking and manualy overclocking i managed to set the ram and cpu. by using asus overclocking tools the divider was changed and the clocks got all messed up. so my advice is do it manually.
  9. Tedster

    Tedster Techspot old timer..... Posts: 10,074   +13

    no. This is because the Front side bus on the motherboard sends to/from the ram TWICE a cycle of charge. You need an oscilloscope to observe this. In other words, it operates two times a cycle instead of 1. So stick of ram that is DDR 6400 runs NORMALLY at 3200 and 6400 in DDR mode. Your motherboard will display 3200 because the DDR function is transparent to the user and the motherboard. If you only used 1 stick of ram, it would not be in DDR mode and would only run in single channel mode at 3200.
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