Ram E.P.P Question

By acacia666avenue ยท 8 replies
Aug 6, 2007
  1. I was reading a customer review for the corsair dominator 1066MHz 2GB DDR2 RAM with E.P.P and is it true that if you have a core2duo and want to turn on the epp, you cant because the Core2Duo fsb speed is 1333MHz. And he also said that thay dont run at 1066 MHz to begin with. He said there 800 MHz sticks that when the epp is turned on they are 1066 MHz. So yea can someone clear this one up if its true or false?
  2. KingCody

    KingCody TS Evangelist Posts: 992   +8

    I'll try to clear this up for ya... (read the bold print for the short answer ;))

    ok first off, don't confuse "effective" speeds with actual speeds...
    -Intel's FSB is "quad-pumped" so it's effective FSB speed = 4 x [actual]. for example, a C2D with a FSB of 1333MT/s has an actual speed of 333MHz.
    -DDR2 is "double-pumped" so it's effective speed = 2 x [actual]. for example, a DDR2-1066 effective speed is 1066MT/s, but it's actual speed is 533MHz. if the C2D's FSB was 1333MT/s then it only needs a DDR2-667 to match it's speed 1:1.

    as for the C2D FSB speeds, only the E6550, E6750, and the E6850 have a FSB of 1333MT/s (333MHz), all other C2D models have a FSB of 1066MT/s (266MHz) or 800MT/s (200MHz)

    as for the RAM speeds, the corsair dominator RAM sticks you're referring to have a default "SPD" spec of 800MT/s (400MHz), but are guaranteed to operate at 1066MT/s (533MHz) when "EPP" is enabled in the BIOS. it's basically a DDR2-1066 RAM stick cleverly marketed as an "guaranteed overclockable DDR2-800 RAM stick". the only difference being that the faster EPP settings are actually programmed into the SPD.

    IMO, EPP is useless. it's just marketing aimed towards people who want to overclock but are unwilling to learn how :rolleyes:... the EPP enabled RAM sticks cost more, so the manufacturer makes more money off of people who want to "overclock automatically". my advice would be to forget about the EPP RAM and read a few basic overclocking guides, and overclock manually instead. if you buy RAM that is fast enough to begin with then you can overclock the CPU without having to overclock the RAM at all, for example instead of buying DDR2-800-EPP just buy DDR2-1066 instead :)

    hope that wasn't too confusing :wave:
  3. acacia666avenue

    acacia666avenue TS Rookie Topic Starter Posts: 45

    thanks, i got it. i was just wondering what SPD is? Ive heard it before.
  4. acacia666avenue

    acacia666avenue TS Rookie Topic Starter Posts: 45

    so are all epp sticks slower than there advertised speed when epp isnt enabled?
  5. KingCody

    KingCody TS Evangelist Posts: 992   +8

    SPD stands for Serial Presence Detect. it's an EPROM chip on the RAM stick that's programmed (from the factory) with information about the specific RAM stick. the BIOS uses this information to set speeds, timings, etc. there are different "profiles" for the RAM stick(s) depending on what speed it is set to run on (it usually sets looser timings as the speed increases, and vise-versa). EPP simply extends these "profiles" for faster speeds.

    I havn't read much about them, but it seems that way.. yes.

    it's basically just an underclocked RAM stick with some extra SPD info programmed into it. like I said before, if you buy RAM that is fast enough to begin with, then there is no need to overclock it (and hence, no need for "EPP" RAM).

  6. Sean Courtney

    Sean Courtney TS Rookie

    I realize that this thread was a while ago but Iam looking at the XFX 780i SLI MOBO which in the specs states;

    Memory Speed (MHz) 800 MHz

    Memory w/ EPP (MHz) 1200 MHz

    Do I have to buy the 800 RAM and set the EPP or can I buy 1066? I am assuming I have to buy the 800 but would like confirmation as I have only become aware of EPP reciently. THX
  7. Tedster

    Tedster Techspot old timer..... Posts: 6,002   +15

  8. Sean Courtney

    Sean Courtney TS Rookie

    Sorry, but nothing there answers my specific question re EPP.
  9. gremlinkiller

    gremlinkiller TS Rookie

    Memory w/ EPP (MHz)

    ok i have the 780i coming in the mail soon and want to no if i can run my detonator ddr2 1066Mhz ram on it the 780i
    i think it only supports 800Mhz but im planing to overclock the Q6600 i have anyway so can i just overclock the whole lot and get it to work???
    or will the ram just not work at all
    also wtf is epp???? something bout auto overclocking so called my ram is stock 800mhz but with epp turned on it can run at 1066 guaranteed by cashair or something that my understanding
    plzz if u no anything about epp ram or my ram and mobo post a comment and help me on this struggle to find a way round this problem thx for taking the time to read and hopefully post back :(
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