Intel C2D E8400, Curious about overclocking

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Punkrulz

[H]ard|Gawd
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Nov 11, 2001
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Hey guys,

My new system is built, and the specifications are in my signature. I definitely want to start getting into overclocking with this CPU after I'm positive everything is running correctly. I presently am also running Windows Vista Business x64. I looked in the thread, and downloaded the following programs:

CPU-Z
HWMonitor
Prime95

First and foremost, I want to confirm that everything is proper with my temperatures. Here is a screen shot of what HWMonitor is reporting:

hwmonitor.jpg


If everything is ok from there, I will feel comfortable continuing on with the OC. Please let me know what you guys think!
 
The CPU core temp looks high. Get RealTemp and double-check the CPU temps (the core temps) to make sure they're reading the same as HWMonitor. The TJMax setting for E8400s is 95C. [edit] The correct temp is 100C, see below.

[edit] RealTemp = here

http://www.techpowerup.com/realtemp/
 
Eggrock,

Real Temp 2.70 reports Core Temperature at 33/34, where as HWMonitor reports 38/39. 5 degree difference across the board. Is 33/34 still where I want to be? This is idle, btw.
 
I think the temperature is being reported incorrectly by the DTS on each core. Mine reads 34C in RealTemp and the sensor test loads the CPU but doesn't cause a change in temps. Same for other things the load the CPU; there's a short delay and then temps. rise steadily up to the max. allowed by the cooling.

Basically, you're never going to know your idle temps without placing a sensor directly on the core.

And for the record, the whole TJMax-DTS=temperature formula is idiotic.
 
Thanks. I am now concerned about a few things, so I think I am going to post over on the motherboard forums. I believe that my multiplier was changing itself. I know when looking in CPU-Z it reported 6x333, and then again in the settings I believe it was 8... so I think it's running some power management changes. I need to figure out what needs to be changed so it isn't automatically changing my multiplier to save settings.
 
That's probably a BIOS change. I have a Gigabyte mobo and it does the same if the CPU isn't being loaded.

[edit] Or maybe disable/uninstall the DES application. I don't remember which, offhand.
 
It was the EIST setting on the BIOS, I was able to look it up and find it. Also known as SpeedStep. I'm going to monitor what happens when I play the game. There was another setting I had to change, as for some reason USB Mouse Functionality was disabled by default... which is strange, I was using a USB mouse and worked 90% fine... hopefully this bumps me up to 100%.

I'm concerned now if there are any other settings that I need to change. Hopefully not, at least not by stock.
 
speedstep is a good thing to have on after you finish overclocking and you know its stable.. less power usage and extends the life of the cpu..
 
I'll make sure to re-enable that once I get everything firmed up. I'm still a little bit leery about the temperatures. Realmonitor was still reporting 33/34 after playing WoW for a little bit... granted it's not any heavily intensive game though. I know HWMonitor System temps went up over 100F supposedly, but core temps were fine. I don't think I'm worried about my cooling anymore though... although I still can't get used to my PC being super quiet!
 
forget HWmonitor its not that good.. i have to use it with my motherboard though but it causes my temp sensors to get stuck randomly.. stick with coretemp or realtemp and make sure you set the TJmax to 95C like eggrock recommended.. at stock speeds the temps probably not going to change all that much on the e8400 mostly because its a really low voltage 45nm.. especially in wow you might see a 10C different.. try running prime95 for a little bit then see if the temps change or not..
 
Will do. So what is the next step for OC'ing this bad boy? I was half tempted to just try setting it to 9x400, though I want to make sure I do this well first to at least get to 3.6GHz. I really need to learn the BIOS options that I have so I can understand everything being changed.
 
Just raise the FSB bit by bit and see if it's stable. Also, make sure you keep your RAM at its lowest possible speed so it doesn't limit your CPU overclock. If you hit an FSB level that isn't stable, go back into the BIOS, raise the CPU voltage a bit (always stay below 1.4V though), and give it another shot. That should be enough tweaking to get you up to 3.6GHz or so, if not more. If you have stability issues, then we'll get into the other voltages and options and see if we can tweak some other stuff to get everything running smoothly.
 
Zero82z said:
eggrock and sirmonkey1985 are incorrect. The proper Tjmax setting for your CPU is actually 100C, not 95C. Also, you should use the latest beta version of Real Temp which already has the correct Tjmax set, and you can get it from here: http://www.fileden.com/files/2008/3/3/1794507/RealTempBeta.zip

That will give you the most accurate temperature readings possible.
Click to expand...

The numbers are all over the place. Here's a decent argument about a 95C setting. Here's another on the anandtech forums

This Intel PDF and processor spec page says 72.4C for the E8400.

The anandtech link above really says it:

The gradient from core temp to Tcase (IHS temp) at FULL TDP LOAD is roughly 23C, if all parameters of testing is exactly same as intel including intel stock cooler, and if tjunctionmax is 95C. This can be worked out from the formula,
Tjmax - Tcasemax = theta(coretocase)*TDP (intel published formula), putting in numbers 95C - 72.4C= gradient 23C or can be worked out from .35c/w * 65W = gradient 23C.
(note if tjunctionmax is 105, then this full load core to case gradient is 33C, and thermal resistance is .5c/w)
This is confirmed by intel stating prochot is set to assert (core junction max reached) when tcase max is reached.

...

But as jaredpace points out, if you keep delta to tjmax at 25-30C, you know you are within specs as your safety margin exceeds any possible gradient, you know you are accurate, and you can ignore all theories and guesses.
Click to expand...

If there are more recent/proven numbers I'd like to know.
 
Is there a way to confirm that my memory is operating in dual channel mode? I've been poking around in the BIOS and haven't seen anything that really relates to that.
 
Punkrulz said:
Is there a way to confirm that my memory is operating in dual channel mode? I've been poking around in the BIOS and haven't seen anything that really relates to that.
Click to expand...
Run CPU-Z and look under the Memory tab. In the top-left corner of the window there will be a box called "Channels #", and it will tell you if the RAM is running in single or dual-channel mode.
 
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