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E8400 (C0), safe voltage?

Discussion in 'Overclocking & Cooling' started by Azuse05, 11 Apr 2010.

  1. Azuse05

    Wise Guy

    Joined: 24 Apr 2009

    Posts: 1,950

    Location: Aberdeen, Scotland

    I've had my E8400 since launch week (before the price hike :p) and run it at stock ever since, it being more than adequate. However it's reached the point where I want the little (3.6?) extra speed when i stumbled across this http://www.legionhardware.com/articles_pages/intel_core_2_duo_e8400_overclocking_guide,1.html which seems ideal since my bios is almost identical plus I could leave the ram running at stock speeds which i'd prefer, since it uses 2.1v by default :rolleyes:

    So I changed the settings and sure enough windows booted @3.6 but the intelburntest v2.4 failed the second pass. I'm assuming because my chip is C0 I'm going to have to bump the cpu voltage up (or have I missed something?) to maintain stability however I've seen many people on here talk about a "safe" 20% over-clock on these cpus and wondering what people regard as safe i.e. voltage and load temps?

    Yes I'm on over-clocking noob, Yes the cooler isn't the greatest but will be replaced by a Thermalright Ultra-120 once the weather starts to warm up.
     
  2. Justintime

    Sgarrista

    Joined: 24 Jul 2006

    Posts: 8,869

    Location: Edmonton, London, UK

    I'd say about 1.35v or thereabouts on air. Likely you'll need less.
     
  3. bifday2k

    Mobster

    Joined: 3 Jul 2009

    Posts: 2,601

    Max vcore u want on air is 1.4v, obviously the lower the better.

    But for 3.6ghz you won't need anywhere near that, unless its a pig of a cpu.

    Make sure the memory to fsb ratio is set to 1:1, put the vcore to say something like 1.2v, save and reboot.

    If it loads windows then use prime 95 instead of intel burn test, as nothing u do on your comp will ever heat ur cpu up as much as ibt, prime is a much better realistic stress program to use (temps wise).

    If it fails with 1.2v, reboot, and up the vcore a notch, untill it dos'nt fail prime, all cpu's are different.

    So basicly stay under 1.4v (load cpu-z reading, not bios reading), stay under 70c for overall cpu temp, or under 100c if going by the cores.
     
  4. Azuse05

    Wise Guy

    Joined: 24 Apr 2009

    Posts: 1,950

    Location: Aberdeen, Scotland

    Hmm, well the bios is now set at 1.3 but cpuz is showing the vcore as 1.248, why such a big difference?

    P.S. Seems to be a pig.
     
  5. bifday2k

    Mobster

    Joined: 3 Jul 2009

    Posts: 2,601

    Its called vdroop, its nothing major really, annoying yes but nothing to worry about really.

    I get bad vdroop on high vcores, for example, i enter 1.55v in bios and its actually 1.475v lol. But low end there is'nt much droop, its all board related really, alot of new ones now come with load line calibration, that helps reduce it.

    But im glad you finally got it working @ 3.6ghz, and yeh not all cpu's are the same, mines 1.12v @ 3.6ghz, same stepping, but i have speedstep turned off and that seems to allow me to tweak my vcore abit more, also iv set my Vtt, and north bridge volts manually instead of having them on auto, which seem to help, both on there lowest or one notch up can't remember lol, south bridge is on the lowest volts too.
     
  6. Azuse05

    Wise Guy

    Joined: 24 Apr 2009

    Posts: 1,950

    Location: Aberdeen, Scotland

    I suppose a better question is why is it 1.264 under full load but 1.280 idle :confused:

    Anyway it's not quite there, cores @56 fails, sun goes down dropping the ambient so the cores hit 53 and remain stable but it's completing the burnin at the same speed it was at 3ghz.

    I think it may be time to upgrade the cooler :D
     
  7. bifday2k

    Mobster

    Joined: 3 Jul 2009

    Posts: 2,601

    Is that prime or IBT, and 56 is'nt high especially if its IBT.

    I used to get my cores upto 65/70c using IBT, ok was abit higher clock but still, hate the thing, thats why i use prime, its much more realistic.

    Your coolers is'nt that bad, i used to use it before i swicted to water, do a 15 min prime small fft run, and let me know the temps then, then i can judge easier.

    And just to annoy you, try and beat 39c core temps using prime small fft :p

    If u don't have it the normal prime for windows http://mersenneforum.org/gimps/p95v2511.zip

    or if u have 64bit windows this one http://mersenneforum.org/gimps/p64v2511.zip
     
  8. Azuse05

    Wise Guy

    Joined: 24 Apr 2009

    Posts: 1,950

    Location: Aberdeen, Scotland

    Oh I just use IBT (v2.4) for cooling usually, heats the cpu far better than prime ever did. It also seems to fail much quicker and saved time is always good. Anyway after much fiddling 1.248v seems to be the lowest stable voltage for ITB max, 25 pass and a couple runs of small/large ftt. Just need to do the 8-12 hour blend.

    It will actually pass them on the two slightly lower voltages, however both of those triggered system restore. I assumed this was bad :)
     
  9. blaineoliver

    Hitman

    Joined: 29 Jul 2009

    Posts: 705

    Location: Near London

    1.36 is Ideal max.
     
  10. Azuse05

    Wise Guy

    Joined: 24 Apr 2009

    Posts: 1,950

    Location: Aberdeen, Scotland

    Eight and a half hours then prime spits out an error :(
     
    Last edited: 13 Apr 2010
  11. bifday2k

    Mobster

    Joined: 3 Jul 2009

    Posts: 2,601

    If prime blend spits out an error at some point it may not be the vcore thats an issue, as if it can do 25 runs on max on ibt, id say thats more then fine.

    But if u want to try and get prime blend stable, try upping the north bridge volts by 1 notch and the same for Vtt.

    Doh! Just spotted your using 4 sticks or ram, yeh deffinatly up the north bridge by a notch or 2.
     
  12. Azuse05

    Wise Guy

    Joined: 24 Apr 2009

    Posts: 1,950

    Location: Aberdeen, Scotland

    Well OCCT was graphing some small voltage drops so I upped the bios one notch to 1.3 resulting in a cpu-z reading 1.248/1.264 under load. Blend has been running overnight for 11 hours now, no error.
     
  13. bifday2k

    Mobster

    Joined: 3 Jul 2009

    Posts: 2,601

    Nice, glad its all stable now.

    Just a quick question, have you set all your voltages yourslef, by that i mean the nb, sb, Vtt and the like?

    As you may be able to get it stable lower then that if you do, i set all my volts to there lowest or 1 notch above lowest, basicly so there not on auto.

    As for 3.6ghz i only need 1.152v (under load), i use a P35 mobo too, might be worth a shot if you hav'nt tried it, save ur current profile though so u can easily go back to it.

    Abit more testing if you hav'nt tried it, but thought id mention it.
     
  14. Azuse05

    Wise Guy

    Joined: 24 Apr 2009

    Posts: 1,950

    Location: Aberdeen, Scotland

    12hrs strait *\o/*

    [​IMG]
     
  15. bifday2k

    Mobster

    Joined: 3 Jul 2009

    Posts: 2,601

    Id deffinatly call that stable then, but we all know how funny computers can be lol, gratz.

    Nice temps too, nothing u do day to day will go over prime levels of heat anyways.