Overclocking E8400 voltage question

[Psynaut]

I got my e8400 stable at 4.0 GHz for 8 hours on Prime 95 by setting my core voltage in the Bios to 1.4225 volts, which I know is a bit beyond the safe zone. The thing is that CPU-Z, CPUID and Everest all show my voltage without a load as 1.24 volts and under load as 1.22 volts.

Now I am new to overclocking but I think I understand that Vdroop is the difference between the 1.22v and the 1.24v number (please correct me if I am wrong), so I know that drop is to be expected. What I don't know for certain is which voltage I should be using for overclocking if I want to stay below the intel recommended 1.3825v or the 1.4v max recommended by most overclockers, nor the reason for the wide disparity between the number I set in the Bios and the 'No-Load' voltage in CPU-Z. As a sidenote I raised my MCH voltage from 1.25 to 1.41 to get a stable overclock, I hope this is within a safe range.

At 4.0 GHz my cores run at 63c and 64c. At 3.8GHz, with a bit less voltage they run at about 61c - 62c. My rig is in my sig.

For overclocking which voltage do I use? I would appreciate any other observations as well.

*edit: Both my heatsink and my CPU are lapped.

 

[BlueWeasel]

For the IP-35 series, I'd trust CPU-z over the BIOS setting. At least, that's what I do with my IP-35E.

The voltage offset on the IP-35 boards is huge (0.10v on my board).

 

[Psynaut]

Thanks for the reply and that makes sense, especially since three seperate programs all give the same voltage reading, but then that brings me to the next logical question which is should my E8400 be capable of being stable at 4.0GHz on only 1.22 volts, or 1.24 volts depending on which voltage I am supposed to use (still not sure about that). Doesn't that seem like kinda low voltage for such high performance?

 

[BuLLBuG]

I have the same question about the voltage , if i clock my 8400 to 3.8 less the 1.35v ,it wouldn't even boot up .
So i pretty jewlous for those who has an e8400 and running 4g stable with less voltage

(BTW : psynaut , i kindda wondering what 's your bios's version ? the 14 ,or the beta 16b09, your Thermalright should handle your e8400 with 3.8 under fullload and less than 55c )

 

[Psynaut]

Bios 14. I didn't even know they had a higher beta version out. Maybe I should try reseating the heatsink to see if that brings the temps down some.

 

[amenx]

Each processor behaves differently, even the same model and even from the same batch. Some could get to 4ghz with as low as 1.32v and others need 1.45 or more. See the huge e8400 thread at XS, you'll see wide variations in vcore.

 

[Psynaut]

Originally posted by: amenx
Each processor behaves differently, even the same model and even from the same batch. Some could get to 4ghz with as low as 1.32v and others need 1.45 or more. See the huge e8400 thread at XS, you'll see wide variations in vcore.

But if CPU-Z, CPUID and Everest are correct, than I got to 4.0GHZ on only 1.22v (assuming that the 'load' voltage is the one to use... since nobody has yet answered my question regarding which is the correct voltage to be monitoring for this) and I am wondering if that should even be possible, and if not, then maybe the voltage in my BIOS is correct in which case I am degrading my chip.

If you guys think it would be possible to get to 4.0GHz on 1.22v under load voltage then I will just be happy that I got a good chip. I guess I am just looking for some guidance...

edit: Btw, My Batch # according to the box is Q743A748 and the pack date was 1/4/08 if that means anything to anybody.

 

[Tempered81]

Originally posted by: Psynaut

Originally posted by: amenx
Each processor behaves differently, even the same model and even from the same batch. Some could get to 4ghz with as low as 1.32v and others need 1.45 or more. See the huge e8400 thread at XS, you'll see wide variations in vcore.

But if CPU-Z, CPUID and Everest are correct, than I got to 4.0GHZ on only 1.22v (assuming that the 'load' voltage is the one to use... since nobody has yet answered my question regarding which is the correct voltage to be monitoring for this) and I am wondering if that should even be possible, and if not, then maybe the voltage in my BIOS is correct in which case I am degrading my chip.

If you guys think it would be possible to get to 4.0GHz on 1.22v under load voltage then I will just be happy that I got a good chip. I guess I am just looking for some guidance...

edit: Btw, My Batch # according to the box is Q743A748 and the pack date was 1/4/08 if that means anything to anybody.

http://forums.anandtech.com/me...=2057083&enterthread=y


1.22vcore at 4.0 is possible. It's fairly low, but possible. Can you prime without errors?

 

[Psynaut]

I did 8 hours on small FFT's with no errors.

 

[Tempered81]

1.22Vcore for 4000mhz priming 8 hours is pretty darn good! Nice chip.

whats the temps?

 

[Psynaut]

At 4.0 GHz my cores run at 63c and 64c. At 3.8GHz, with a bit less voltage they run at about 61c - 62c. Both the Heatsink and the CPU ar lapped. Based on what Bullbug said I wonder if I should try reseating my Heatsink to see if I can bring the temps down. At idle I think they were around 43c, but I am going by memory and could be wrong.

 

[aussiestilgar]

Originally posted by: jaredpace
1.22Vcore for 4000mhz priming 8 hours is pretty darn good! Nice chip.

Did you see that he has set 1.42v in BIOS, and after Vdroop @ load hes at 1.22? Thats a huge 0.2v Vdroop. I don't know much about the Abit boards, but that seems very high.

In any case, with that cooler and those temperatures (if accurate) you sound like you're fine. If you're worried about the high Vcore, try raising FSB, NB voltages and lowering RAM speed etc. that may allow you to lower Vcore and still keep it stable.

 

[Psynaut]

Hard to know if the temps are accurate given the issues with the e8400, but they are consistent accross all the programs I used to measure them

I have already raised the North Bridge voltage from 1.25 to 1.41 and I haven't been able to locate anywhere information that tells me what a safe maximum voltage is for the MCH so I have been nervous to go any higher.

Also, I have not been able to figure out how to raise the voltage to the FSB. I have the ratio set to 1:1, but don't know where to change the voltage setting. I have read at least basic 6 overclocking guides, but can't find an advanced guide anywhere.

KNowing this would allow me to try it.

 

[boshuter]

The Q743A's are really good for the most part. Mine is stable at 4.3ghz with 1.35vcore. All the P35 boards I've ran undervolt the vcore like that, I measure mine directly off the board with a dmm and it's right on with what CPUZ reads.

 

[dino26]

I have an e8400 @ 3.6 and have not changed a thing voltage wise. It is perfectly stable and i get about 16750 3dmark 06 default with CF hd3870. I also tried 1.8ghz and it boots and runs some games. 3dmark and crysis both ususally crash at some point @ 3.8. I suppose if i raise some volt I should be able to do 3.8 or 4.0? not sure what volts to raise? Just Vcore? I suppose also to lower ram from 44412 to 55515? I am only using pc800 ddr2 but its good ram. I heard a lot of pc800 can do 4ghz?

 

[GuitarDaddy]

This seems to be common to all the Intel chipset boards, I've heard it referred to as

Vdrop = bios > CPUz idle
Vdroop =CPUz idle > CPUz load

On my P965 board it is huge and it gets worse as you increase the voltage. For instance to get 1.3 under load I have to set 1.425 in bios, to get 1.38 under load I have to set 1.5875


If you really want to run a max overclock 24/7 you should find and perform the vdroop volt mod for your board

 

[PinkPanther1970]

Originally posted by: dino26
I have an e8400 @ 3.6 and have not changed a thing voltage wise. It is perfectly stable and i get about 16750 3dmark 06 default with CF hd3870.

That is because you leave your vCore at "auto" in the bios.
When I put my FSB at 400 and leave vCore at "auto", it automatically raises the vCore to 1.3 in the bios (1.28 idle and 1.26 under load in Everest).
So your machine is not running at 3.6GHz at standard 1.225 vCore.

 

[Psynaut]

Originally posted by: dino26
I have an e8400 @ 3.6 and have not changed a thing voltage wise. It is perfectly stable and i get about 16750 3dmark 06 default with CF hd3870. I also tried 1.8ghz and it boots and runs some games. 3dmark and crysis both ususally crash at some point @ 3.8. I suppose if i raise some volt I should be able to do 3.8 or 4.0? not sure what volts to raise? Just Vcore? I suppose also to lower ram from 44412 to 55515? I am only using pc800 ddr2 but its good ram. I heard a lot of pc800 can do 4ghz?

Yes, that is what I am using. I have my voltage set at 2.2v for the Ram and timings of 4-5-5-15 and it runs Crysis without crashing. I have not yet had time to try tightening the timings or lowering the voltage so I can possibly do even a little better than this.

I also had to raise my MCH voltage from 1.25 to 1.41 in order to get to 4.0GHz since I am using 4 X 1GB sticks. From what I read if you are using 4 sticks of Ram it helps to raise this voltage a small amount since it controls the memory. Hopefully, I haven't raised it too much; I have had a hard time finding out what a safe max voltage is but this doesn't seem like alot so I think I am probably safe.

As an update to my original problem, I just flashed to the latest Beta BIOS and now my 1.4225v in the BIOS reads out under load at 1.35/1.36 with CPU-Z, which is significantly closer than the 1.21v I was getting before. I still read 1.25 idle, but I think that has to do with some power savings settings. I will look into it tomorrow and report back if I find anything interesting.

 

[Psynaut]

Originally posted by: BuLLBuG
I have the same question about the voltage , if i clock my 8400 to 3.8 less the 1.35v ,it wouldn't even boot up .
So i pretty jewlous for those who has an e8400 and running 4g stable with less voltage

(BTW : psynaut , i kindda wondering what 's your bios's version ? the 14 ,or the beta 16b09, your Thermalright should handle your e8400 with 3.8 under fullload and less than 55c )

I just switched to RealTemp, which is a program designed to give accurate E8400 temp and it shows my temp under full load at 60-62c. Thanks for the heads up on that, I will try reseating the heatsink..

Oh, and I just flashed to BIOS 16b10, which just came out.

 

[dino26]

OK so i messed with my system a little more and finally figured out how to change my vcore for the asus p5e. you have to hit spacebar at auto and then type in the voltage manually.

I did not realize how the auto vcore worked...i assumed it adjusted some. I was not able to run my system 100% stable at 3.8 ghz with vcore at auto however. I changed it to 1.35 last night and 3.8ghz is perfectly stable after running 3dmark a couple times, crysis , and a few other things. My new 3dmark06 default score went from 16750 to 17570 and that is with only one hd3870 oc and the other at normal temp. I am using a all copper zalman orb for the cpu and the 3870's are using stock cooling. I did however order 2 accelero s1 with turbo to help. My 3870's were running at least 70-75c at load with not a large oc so I hope the s1's help. oh and i didnt check load but at idle my e8400@3.8ghz only runs at around 36c so maybe I will try a 4ghz oc. I am a little concered my 800ddr2 might not be able to handle it. I will post back tomorrow with my results.

Also I will try less than 1.35v for 3.8ghz since that is the only setting i tried so far and it works. I suppose less voltage is always better as long as things are stable.

 

[dino26]

uppdate on voltage and oc

So last night I tried a few things with my e8400. First off i tried 3.8ghz with lower volts and it didnt seem 100% stable at less than 1.32 volts. I was also able run a stable os at 3.87ghz at 1.36 volts. 4.0ghz at 1.4 volts worked fora while it windows then finally crashed when attempting 3dmark so I think I will stick with 3.8ghz since I dont have to raise the volt much and it is stable. I have a feeling that 4.0 could be doable especially if i went to water but I dont think i want to risk anythign setting that up (I have parts for water) with such a high power system as is.

 

[lou61166]

Originally posted by: dino26
uppdate on voltage and oc

So last night I tried a few things with my e8400. First off i tried 3.8ghz with lower volts and it didnt seem 100% stable at less than 1.32 volts. I was also able run a stable os at 3.87ghz at 1.36 volts. 4.0ghz at 1.4 volts worked fora while it windows then finally crashed when attempting 3dmark so I think I will stick with 3.8ghz since I dont have to raise the volt much and it is stable. I have a feeling that 4.0 could be doable especially if i went to water but I dont think i want to risk anythign setting that up (I have parts for water) with such a high power system as is.

I also got mine to 4.0 GHZ,at 1.4 volts,it ran great passed all stress tests,temps 40 idle 58 under load ,the problem began when i tried to shut it down,it stopped windows fine but the fans kept running i had to manualy shut it down with the switch,when i went to reboot it again it said overlock failed,so i lowered the bus down to 430 at 3.8 ghz,1.35 volts it runs great again and it will shut down fine,temps 35 idle 50 under load.

 

[dino26]

yeah i had mine do the same thing actually.

 

[Dadofamunky]

Not that this directly addresses your question, but I have 13 Hr. stable in Prime with an e6750 at 3.7 GHz, and no problems shutting down. My voltage settings are a bit beyond the pale, at 1.55V (max safe zone from intel specs). Under load it never gets beyond 1.42V. So I've got this thing OCed to the eyeballs.

I think I'd crank it up to 4 if I were you, with the settings you had it stable at, and not worry. Your temps were very good and didn't budge much from slightly lower settings. Then again, I plan on cutting over to a 9 multiplier CPU in 6 months or so, so a few months of life cycle off my e6750 doesn't matter much to me. (Now, if I fried my chip, that WOULD matter, regardless.) Just my two centavos.

 

[djplayer]

I currently run stable @ stock voltage of 1.11V 3.6ghz. If you touch 1.5V you're gonna hurt your cpu's lifespan.. I can hit 4.4ghz stable if I up the Voltage to 1.45. unfortunately I have to clock my ram a little lower b/c it gets very touch.