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Overclocking e8400 to 4ghz, need help!

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Hurlbag

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Jul 27, 2010
Hi, so for awhile now i've been trying to overclock my e8400 up from 3.6 to 4ghz, but keep failing. I think the issue is possibly my RAM? my board is limited to supporting 800mhz RAM but from what i've read I need to set DRAM frequency to 445mhz in order to achieve 4ghz on my CPU.

I'll put my spec at the bottom of this post - at the moment my CPU is set at 1600 FSB and RAM is set at 800, giving me 3.6ghz.

In trying to get 4ghz I set my RAM to 890 and CPU to 1780 FSB - that's correct if i'm mistaken? well anyway I set my Vcore to 1.39 (my mobo undervolts so it's a bit less) NB, SB and HT in the 1.5 - 1.6v range, and RAM to 2.1 - 2.2v.

No success, got various problems loading up such as 'BOOTMGR failed' and 'Windows is loading' in the safe-mode DOS visual (in which it would reboot after 'loading').

What am I doing wrong here? i've read people getting the 4ghz mark with the same system specs as me but I can't seem to do it, any help/advice would be briliant, thank you for reading.

e8400 3.6ghz
2x2gb Corsair XMS2 800mhz RAM (5-5-5-15)
Asus P5N-D nForce mobo
GTX 460 1gb
 
Loosen the timings on the ram or give the ram .1v over its stock rating.

Check out the C2D/C2Q overclocking guide (link found in my signature).
 
And also give these settings a try for 4.0GHz (445MHz x 9), w/ DRAM frequency at DDR2-890...

Code: 
Vcore Voltage: 1.4
HT Voltage: Auto
NB Chipset Voltage: 1.45
SB Chipset Voltage: Auto
FSB (QDR): 1780 (445MHz x 9)

RAM Linked and Synced at DDR2-890, and 5-5-5-15 timings.
 
Thanks for the replies, though still no success :(

I loosened my timings quite alot, tried 6-6-6-18, 6-6-6-24 and 7-7-7-24 which only got me worse results :/

I will try your voltages redduc900 though already used those timings/FSB, will see if it makes a difference.
 
No luck, think maybe I just need a new motherboard? I have had mine for atleast 2-3 years now, and it has been making a strange oscillating noise whenever I move the mouse for some time now.. :sly: (not sure if that's something to worry about?)
 
Post the stepping (found by opening CPU-Z to the CPU tab) and VID (found by opening Real Temp to the Settings page) of your chip. Next run Memtest86+ at 5-5-5-15-2T and whatever the rated Vdimm is at DDR2-800, this w/ the settings I posted above.
 
redduc900 said:
Post the stepping (found by opening CPU-Z to the CPU tab) and VID (found by opening Real Temp to the Settings page) of your chip. Next run Memtest86+ at 5-5-5-15-2T and whatever the rated Vdimm is at DDR2-800, this w/ the settings I posted above.
Click to expand...

Bob,

Will his Corsair RAMs overclock that much? I never know how much RAMs will overclock past their defaults so that's why I always buy more than I need. :-/
 
Stepping is 6, VID is 1.2250, will run Memtest 86+ soon, thanks
 
RollingThunder said:
Bob,

Will his Corsair RAMs overclock that much? I never know how much RAMs will overclock past their defaults so that's why I always buy more than I need. :-/
Click to expand...

I had a set of XMS DDR2-800 that wouldn't OC 1MHz over stock, no matter the voltages or timings. So, I skeptical about his RAM.

Hurlbag said:
Stepping is 6, VID is 1.2250, will run Memtest 86+ soon, thanks
Click to expand...

By stepping he meant C0 or E0, which is actually listed under "Revision" in CPU-Z for some reason :shrug:
 
Oh right, well it's C0 then. Ran Memtest86+, no errors at those timings either. Will try the standard vdimm but I can't see it working, as RollingThunder said maybe I just have really stubborn RAM? :shrug:
 
Hurlbag said:
Oh right, well it's C0 then. Ran Memtest86+, no errors at those timings either. Will try the standard vdimm but I can't see it working, as RollingThunder said maybe I just have really stubborn RAM? :shrug:
Click to expand...

Not so fast! Redduc is much more experienced on this than I am. I was only thinking out loud. RAMs are unpredicable to their overclocking abilities past their defaults. Give it a shot with his suggestions, you can't hurt anything.
 
Success!! :rock:

I've finally managed to get it stable enough to run Windows at 4ghz, somehow turning off 'Disable XD bit' and 'Intel Virtualization technology' made it possible.

I've read Disable XD bit feature helps against viruses in some way, is it dangerous I have that turned off?

Upped my Vcore to 1.41 (reads 1.36 in CPU-Z)
NB set to 1.48v, HT SB set to auto and VDIMM at 1.95v.

CPU Tempreature is sitting idly around 48-50, sounds normal enough for an e8400 @ 4ghz right? will see if I can lower the Vcore and retain stability anyway. *happy*

Thanks to those who posted^^
 
Last edited:
Hurlbag said:
Success!! :rock:

I've finally managed to get it stable enough to run Windows at 4ghz, somehow turning off 'Disable XD bit' and 'Intel Virtualization technology' made it possible.

I've read Disable XD bit feature helps against viruses in some way, is it dangerous I have that turned off?

Upped my Vcore to 1.41 (reads 1.36 in CPU-Z)
NB set to 1.48v, HT SB set to auto and VDIMM at 1.95v.

CPU Tempreature is sitting idly around 48-50, sounds normal enough for an e8400 @ 4ghz right? will see if I can lower the Vcore and retain stability anyway. *happy*
Click to expand...

A word of Caution: Your idle temps are high. Did you run Prime95 or Orthos and check them? If you're hitting ~72C+ or more, then you need to have a better cooling solution.

Passing Memtest86 is only the first step, run SuperPi 32mb test and if it passes, then run your Prime95 or Orthos tests watching your temps all the time.

My board has the BIOS shutdown set at 70-71C if I'm not here watching. It's a little conservative but Intel recommends no more than 74C for this series of chips.
 
Hmm I loaded up Starcraft II to see how stable it is, and within 5 minutes my PC instantly just powered off, without crashing or anything.
Never has my PC done that, is that a sign my PSU is failing or lacks sufficient power for my OC? kinda concerned for the rest of my system, will run Prime95 and see what happens.

edit: Just read your post, i'm guessing my CPU must have broken the 72c limit. I did monitor the temps while playing, and the max I saw a minute or two before the shutdown was 62c. Will run SuperPi first then.
 
Hurlbag said:
Hmm I loaded up Starcraft II to see how stable it is, and within 5 minutes my PC instantly just powered off, without crashing or anything.
Never has my PC done that, is that a sign my PSU is failing or lacks sufficient power for my OC? kinda concerned for the rest of my system, will run Prime95 and see what happens.

edit: Just read your post, i'm guessing my CPU must have broken the 72c limit. I did monitor the temps while playing, and the max I saw a minute or two before the shutdown was 62c. Will run SuperPi first then.
Click to expand...

This is where caution is needed. Corrupting your operating system without a thorough test of stability is a good possibility. Your taking a big jump from 3.6 to 4.0 Mhz without testing it in between with no idea at what point your overclock is failing. Go back to 3.6 and run all those tests before increasing your overclock.

Our chips are similar and I'm at the max I can get with standard CPU voltage (1.18v) and stock cooling without entering the danger zone of 74C. If you're using the stock Intel cooler at 1.4v, I don't think you're going to make it. These chips are great overclockers but not without better cooling.
 
RollingThunder said:
Bob,

Will his Corsair RAMs overclock that much? I never know how much RAMs will overclock past their defaults so that's why I always buy more than I need. :-/
Click to expand...
They should run at 445MHz w/ no problems Dave, since it's only 90MHz above the default frequency. If not, then a slight bump in DRAM voltage or slightly looser sub-timings should do it.

@ Hurlbag... Your chip is probably going to need >1.4-1.41 Vcore because it's an older C0 stepping w/ a somewhat high 1.225V VID.
 
Ok so I did some tests earlier, passed SuperPi on 32 & ran Prime95 for over an hour, the max temp obtained was 64c - dropping down to 46-47 idle.

Tried Starcraft II again and had the same thing, even though the max tempreature only reached 62c before shutdown. I'll try sticking the voltage up to 1.41 as you suggested and see if that helps.
 
Hurlbag said:
Ok so I did some tests earlier, passed SuperPi on 32 & ran Prime95 for over an hour, the max temp obtained was 64c - dropping down to 46-47 idle.

Tried Starcraft II again and had the same thing, even though the max tempreature only reached 62c before shutdown. I'll try sticking the voltage up to 1.41 as you suggested and see if that helps.
Click to expand...

HB,

Out of curiosity, what's your power supply?

Your temps are ok and I'll defer to redduc on his suggestions to you.
 
Currently using a 'Trust' 550W PSU.

Upped the voltage, but the problem seems to persist - i'm not sure what's causing it but under load in Starcraft II, one of the components in my PC starts making rapid 'static' clicking noises, followed by PC shut down (max temp before shutdown was 66c).
Never heard this sound before so I assume it's either the CPU, RAM or PSU? as I can't see how overclocking would affect the fans as they're set to a fixed value.

Even with the voltage up to 1.41 this still occurs, only 2-3c temp gain. It's perfectly stable running Prime95/any other task in windows.

The noise it produces under load really concerns me, though the tempreature still doesn't exceed 66c - what else can I do? :eh?:
 
Think I just found the problem, assuming it was the PSU I turned the clock speeds on my GTX 460 to stock, and the fan down to 40% (from 60%). Loaded up Starcraft II, no noise, stable and been playing for about 20-30 mins now with no issues (whereas before it'd cut out after 2-3 mins).

Pretty sure I was straining my PSU, guess i'll get me a new one.
 
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