# E8400 oc



## bizoot (Jan 27, 2009)

my current system:
processor
intel core 2 duo e6750 2.66 right now OC'd to 3400MHZ (425X8)
MOBO
GIGABYTE GA-P35C-DS3
RAM
CORSAIR 2X1GB 1066MHZ
CORSAIR 2X1GB 800MHZ
(TOTAL 4 GB)
CPU FAN
******** VENDETTA 2
my question is...
If I buy an E8400 processor, which stable speeds should I be able to reach with it?
And what will limit me? My mobo? Ram? I know for sure my slow ram (800MHZ) will limit me, but if I remove it, will my mobo still limit me? (Remember, right now I'm at 425X8).
THANKS!!!


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## greenbrucelee (Apr 24, 2007)

all cpus are different, I got my e8400 to 4GHz without issue but you may not be as lucky as me.

what is your psu? and what wattage? the psu is very important when it comes to overclocking and if you have an inferior brand then you could be asking for trouble.

Your ram isn't that slow, you may get to 3.6 with it but its all about experimenting


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## bizoot (Jan 27, 2009)

my 2.66 is now at 3400.
I'm not planning on buying a new cpu just for an extra 200 mhz...
my psu is corsair tx750w
thanks


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## greenbrucelee (Apr 24, 2007)

you would get better results if all your ram was the same speed. Having two different speeds of ram in your pc can cause big problems.


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## bizoot (Jan 27, 2009)

suppose I remove the 800MHZ ram and replace it with 2 more gigs of 1066MHZ?
What then?


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## greenbrucelee (Apr 24, 2007)

you should have all four slots filled this can have bad results, if you want 4GB then you would better off with 2 2GB in slots one and three.

You mentioned that you redid the paste and heatsink you shouldn't overclock until the paste beds in and if you used artic silver 5 it takes 200 hours to do it so you might see a drop in temperature of a couple of degrees after it has bedded in.

Then you need to start raising the FSB in small steps and each time you do see if it boots into windows. Overclocking can be a very lengthy process if done properly.

Read this to get some ideas http://www.techsupportforum.com/f27...erclocking-read-here-for-starters-232382.html

The post back when you need help.


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## bizoot (Jan 27, 2009)

I used the paste I got with the cooler (ocz vendetta 2). what happens if I don't wait 200 hours?
and should I really replace all my ram just because it's gonna be in 4 sticks?


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## Wrench97 (May 10, 2008)

4 sticks can sometimes cause stability issues, try it with the 4 you have and see what happens Overclocking results are different on all motherboards/cpu's with all the ram slots filled you sometimes need to raise the NBridge voltage which can raise temps and cause instability, other times not, you need to test it.


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## greenbrucelee (Apr 24, 2007)

The paste needs time to bed in properly to achieve maximum conductivity between the cooler and cpu. Some people overclock straight away but doing this you risk not getting a drop in temps.

For example:I rapplied my paste last week (Wednesday) and I am seeing idle temps of 37 degrees c once the paste has bedded in I should hopefully see a drop in that idle temp it can be between 2 and 5 degrees then I will reapply my overclocking settings and hopefully be able to get more out of it


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## bizoot (Jan 27, 2009)

So I OC'd my E8400
450X9, 1.3500 VCore.

I ran OCCT but after 5 minutes it crashed because it reached the max cpu temp (which I changed from a default of 80 celcius - to 72).
I changed it to 72 because I saw on the intel website that the thermal specification is 72.4 celcius for this cpu.

Is this really the highest temp recommended? Or could I set the max temp a bit higher??
Thanks!


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## greenbrucelee (Apr 24, 2007)

72.2 is the highest for that cpu but you should be aiming not to go above 60

I overclocked my cpy to 3.5 tonight before I go back to 4GHz at the weekend and my max temp was 45, lower your voltage.


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## greenbrucelee (Apr 24, 2007)

what are you using to monitor your temps?

you should be using real temp as this is the best for 45nm core 2 duo CPUs, download it if you don't have it and set the thermal junction setting called TJ max to 95 for both cores this will give you proper temp readings.


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## bizoot (Jan 27, 2009)

I'm using the occt itself and HWMonitor.
What does "TJ max to 95" mean?
is this the max temp I want to reach???


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## bizoot (Jan 27, 2009)

now I watched a streaming movie from a website on fullscreen and after about 40 minutes the picture froze and I had to shut down.
I changed the OC settings to 445X9, 1.325 VCore.
right after boot, I started HWMonitor, and a few seconds later I saw the max temp of core#0 spiked up to 64 celcius (core#1 max temp is still at 58 degrees only)!
Is this ok? I don't understand, even after lowering the vcore why does this happen?


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## greenbrucelee (Apr 24, 2007)

bizoot said:


> I'm using the occt itself and HWMonitor.
> What does "TJ max to 95" mean?
> is this the max temp I want to reach???


HW monitor wont report the correct temps it will probably be 5 degrees c higher than what it actually is. I have HW and it reports mine as 42 degrees c idle when infact its 37

You need to download real temp and set the TJ max to 95 for both cores.

TJ max is the thermal junction setting which in laymans terms means what the maximum thermal resistance of the cpu is.

If you have real temp functioning whilst you have Prime95 stress testing your cpu you will see the TJ max going up and down on both cores what you do not want is both cores saying zero or both cores saying 95 because this were the thermal resistance is non exsistant meaning the cpu will die or overheat.


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## greenbrucelee (Apr 24, 2007)

bizoot said:


> now I watched a streaming movie from a website on fullscreen and after about 40 minutes the picture froze and I had to shut down.
> I changed the OC settings to 445X9, 1.325 VCore.
> right after boot, I started HWMonitor, and a few seconds later I saw the max temp of core#0 spiked up to 64 celcius (core#1 max temp is still at 58 degrees only)!
> Is this ok? I don't understand, even after lowering the vcore why does this happen?


you need to get those temps down but that being said if your using hardware monitor it will be wrong so by my calculations if you download real temp you should see 59 and 53 which is acceptable although I would prefer core 1 to be lower than that. Don't worry that both cores are different temps remember core 1 is ontop of core 2 so obviously core 1 will get hotter than core 2.

I think you should be aiming for 443 x 9 with a vcore of 1.218 thats how I had my 4GHz setup


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## bizoot (Jan 27, 2009)

OK I've been running prime95 for about 2 hours and using real temp v3.0 to monitor temps.
I see the max temp reached by both cores is 66 degrees.
distance to TJ max is about 31 in core#1 and 33 in core#2...


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## greenbrucelee (Apr 24, 2007)

bizoot said:


> OK I've been running prime95 for about 2 hours and using real temp v3.0 to monitor temps.
> I see the max temp reached by both cores is 66 degrees.
> distance to TJ max is about 31 in core#1 and 33 in core#2...


have you changed the TJ max to 95 for both cores in the settings?


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## bizoot (Jan 27, 2009)

yes sir


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## bizoot (Jan 27, 2009)

is that ok?
so what are the final conclusions?


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## greenbrucelee (Apr 24, 2007)

to me your temps are too high 66 is below the cut off point but its not that far of it. I would look at other cooling solutions like a better cpu cooler and creating more airflow in the case


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## bizoot (Jan 27, 2009)

And something else...
I didn't understand why I needed to set the TJmax value in real temp to 95...
Does this mean that 95 degrees Celsius is the highest temp I am willing to allow?
Isn't this a bit high? considering intel recommends 72 degrees only?
Thanks.


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## Phædrus241 (Mar 28, 2009)

The TJMax is the "thermal junction maximum", basically it's just a number used to calibrate the thermocouple used to determine temperature inside the CPU. It doesn't affect the shutoff point or anything, it's just a calibration thing.


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## bizoot (Jan 27, 2009)

Anyhow, my computer kept shutting off every day or so...
So I decreased the OC to 440X9 (1.2 VCORE).
Is this OK?
Thanks!


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## greenbrucelee (Apr 24, 2007)

test it with prime 95 for atleast 7 hours if you don't get any errors it is fine just make sure your temps are good too by having real temp displayed whilst prime95 is running


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## bizoot (Jan 27, 2009)

On another forum, someone wrote this...

450x4 = 1800mhz always multiply your system bus frequency (fsb) by 4.
cpu frequency 450x9= 4050mhz that's mega high. atleast you know your chip can reach that frequency.

the maximum system bus frequency your motherboard handles is 333x4=1333mhz. so your pushing your system bus frequency to high more that the board supports, so therefor will cause damage to your motherboard.

Is this correct???


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## greenbrucelee (Apr 24, 2007)

your mobo supports fsb of 800,1066 and 1333. The e8400 is 1333 and is 333 x 9. If you take out the 800MHz ram you will probably get better results because of the 1066MHz frequency.

If you get as far as me 443 x 9 with the ram at 886 which makes a 1:1 ratio

450 is too much in my opinion even if you have dropped the multiplier.


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## bizoot (Jan 27, 2009)

Do u think the system crashes at 450*9 because of the 800MHZ ram stick I left inside?
Or is it simply to high for my mobo/cpu?
thanks...


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## mattlock (Dec 28, 2005)

bizoot said:


> And something else...
> I didn't understand why I needed to set the TJmax value in real temp to 95...
> Does this mean that 95 degrees Celsius is the highest temp I am willing to allow?
> Isn't this a bit high? considering intel recommends 72 degrees only?
> Thanks.


Tjunction max is the approximate core temperature that the CPU will shutdown. It varies from one CPU to next. (CPU throttling typically begins a little before the TJ max and Thermal Trip usually just after TJmax.) 

The Tjunction temp is measured by the digital thermal sensor (DTS) embedded in each core. The 72.2c that is referred to by Intel is the Tcase max, which is the temp at the center of the heat shield on the CPU. The problem with useing the Tcase max as your target temp, is there is no sensor to read that temp. The Tjunction temp is always going to be higher the Tcase temp. 

I prefer to stay under 60c but a good rule of thumb is stay at least 30c under your TJmax. The default TJmax for Real Temp used to be 95° and Core Temp was 105°. Both utilities now default to 100°c for 45mn CPUs, which is the Tj Max that I use. So you max safe operating temp is 65-70° (depending on the Tjmax you use 95° or 100°)



bizoot said:


> Do u think the system crashes at 450*9 because of the 800MHZ ram stick I left inside?
> Or is it simply to high for my mobo/cpu?
> thanks...


If you're not running a memory divider to keep your ram running 1:1 then that's highly likely. At 1:1 your ram would be running at 900mhz on a 450mhz fsb. I have the same 800mhz ram and didn't run into problems until I hit around 940mhz. What's your RAM voltage setting? 

Other thoughts, considering the fact that you are running an after market heatsink/fan your temps are pretty high.(at 1.4v I wasn't close to 70° on my 8400) I don't think they would be that high with the stock fan. I recommend that you replace the paste that came with your HS/F with some Arctic Silver and remember, too much thermal compound is just as bad as not enough. If it's oozing over the edge of the heatshield it's too much.

Also, you're running a 32bit OS so 4GB of memory is not usable. Your usable memory is closer to 3GBs due to limitations of the 32bit OS. So there is not a big advantage to running 4gb vs 2gb


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## bizoot (Jan 27, 2009)

I now have windows 7 64 bit...
And as for the thermal paste, 
The tech guy at the store when he connected my cpu, he applied a paste that came with a brush... Silver color...
I'm almost sure it was "‏Zalman Super Thermal Grease ZM-STG1"
And he didnt apply to much... he smeared it evenly and in a thin layer...


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## mattlock (Dec 28, 2005)

ZM-STG1 is a pretty compound, pretty comparable to AS5. I still prefer AS5 however. 

What kind of case do you have and what's the case fan configuration? (how many case fans, where are they located, do they suck air into the case or exhaust it from the case?)

What are your RAM timings and voltage?
What is your memory divider set at?


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