Having trouble with overclocking e6400

Hi, Im new to overclocking and trying to oc my Core 2 Duo e6400 from 2.13 to 2.5Ghz, and possibly more when i get better cooling, but whenever i raise the fsb from 266 up to about 300 my pc bluescreens just before windows boots.

I've tried increasing the voltage slightly and my RAM frequency is set to auto timings are 5-6-6-18 ive turned off all extra features e.g intel speedstep, non of this makes any difference.

I've also tried lowering multiplier but no change.
oh also there are different jumper settings on the mobo dont know of i need to change them. Havent tried, dont want to screw it up.

pls help :)

Mobo - Asrock p41c-de
CPU - Core 2 Duo e6400 @ 2.13Ghz
RAM - 2gb Kingston 800mhz single channel
GFX - Geforce 9600gt
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More about having trouble overclocking e6400
  1. Take your RAM off the Auto setting and set your memory clock to 533 MHz (twice the FSB freq). I am unfamiliar with the Asrock BIOS, so I cannot tell you how.

    The big problem here is that different BIOS' define terms slightly differently.

    My definitions (extracted from an old post):

    Definition time (attention purists, I'm talking about DDR2 and I'm simplifying a little :)):
    Core2 CPU's use a frontside bus (FSB). The FSB is a thing with two main characteristics: speed which is usually defined in MHz and width which in the Core2's is 64 bits wide. We are concerned with the speed.

    Using the Q6600 as an example, the FSB frequency is 266 MHz. The matching DDR2 memory clock for that frequency is 533 MHz (266 X 2). DDR2 memory transfers two chunks of data for each bus cycle, hence double the frequency. So, to run 1:1 at an FSB of 266 MHz, we need DDR2-533 RAM. What CPUZ does is a little confusing. It will tell you that the memory frequency is 266 MHz for a 1:1 ratio.

    The FSB clock is 1066 MHz (266 X 4). The bus is "quad pumped". It transfers 4 chunks of data into and out of the CPU each cycle. So each FSB cycle generates 4 FSB clocks.

    Now, if you increase the FSB frequency to 333 MHz, the corresponding memory clock is 667 MHz and the FSB clock is 1333 MHz.

    I always run my memory at 1:1. That is the FSB freq to mem freq ratio of one to one. That means that the memclock is twice the FSB freq. It's a little confusing. Running memory slower costs performance. Running memory faster does not give you much if any real world performance increase and it can lead to higher instability.

    Once you get the memory sorted out, the upper limit that you can expect is around 2.8 - 2.9 GHz. This limit is imposed by the motherboard chipset. The G41 is an economy chipset with an upper FSB freq of about 350 - 360 GHz (if you are lucky :)).

    CPU Vcore limits for the Conroes is 1.5 volts.

    I have three G'byte G41 systems doing office type stuff. One has an E6500 (2.93 GHz Wolfdale core) running at 3.8 GHz.
  2. Hi jsc, well I tried what you recommeded and changed RAM frequency to 533Mhz,
    then I increased the fsb to 333, (but wouldn't this overclock the RAM quite a bit?)
    Anyway after doing this and restarting the computer it would not boot, so I reset the bios.

    I think I may have sorted it though, i adjusted the jumpers on the motherboard so I could overclock to 1333Mhz and the RAM would still run at 400Mhzx2 and so far so good, no bluescreens.

    Ive only got it at 2.4Ghz but still thats better than before :D.

    Thanks for your quick reply JSC ;D
  3. The problem is when you raise your fsb your raising the ram speed past it's design therefore causing blue screens.

    Change the fsb/cpu ratio so that the ram stays under 800mhz (400x2).
  4. Thats what Ive done, Its running at 2.66Ghz at the moment until I get better HSF, then I'll probably push it further.

    Alls working fine, thanks for the replies. ;D
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