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windows versus bios voltage

Discussion in 'Overclocking & Cooling' started by vishal, 26 Jan 2006.

  1. vishal

    Associate

    Joined: 3 Dec 2005

    Posts: 31

    i have my opteron at 2.5 ghz on 1.4volts in bios but in abit eq it says it is 1.44 volts and in cpu z it says it is 1.439 going up to 1.466. it seems to fluctuate a lot in cpu-z between those to voltages.

    my question what is the real voltage to believe?
    my psu is an antec neohe 430
     
  2. twiceborn

    Gangster

    Joined: 31 Oct 2004

    Posts: 287

    Neither. The only way to get an accurate voltage reading is to use a multimeter, as onboard monitoring is notoriously unreliable.

    However, I suspect the readings in the BIOS and in CPU-z are the same - just it's different in Windows as the load is different. I'd recommend only using the values reported in these programs for relative comparisons, rather than absolute ones. What I mean to say is, use them to see if you get, for example, a big drop when you load the processor, but don't worry too much about the actual values they report. If these values DO worry you, get a multimeter ;)
     
  3. vishal

    Associate

    Joined: 3 Dec 2005

    Posts: 31

    well uguru utility says it is 1.43 - 1.45 in bios as well. it doesn't vary with load (like when i use prime95).
    the reason i wanto know is i want to know what is safe to oc to.
     
  4. NightSt@lk3r

    Sgarrista

    Joined: 7 Dec 2005

    Posts: 7,603

    Location: Wiltshire

    only true way to know is to use a DMM, windows gets its voltage readings from the same probes as the bios so they will give the same readings
     
  5. twiceborn

    Gangster

    Joined: 31 Oct 2004

    Posts: 287

    Sorry - I wasn't paying enough attention when I read the first post. I see what you're saying now - CPU-z gives different readings from uguru, but both are in Windows, so where are the readings coming from?

    I'm afraid I don't know :o I've noticed this sort of difference before with Windows motherboard monitoring programs (it happens with temp readings as well) and I've never understood it - they use the same probes, as NightSt@lk3r says, so why return different values? No idea, LOL.

    As for overclocking, go by whichever program reports the highest, just to be safe. Stay below 1.55V (some say 1.6, some 1.5) if you're on air cooling, but watch your temps! Try to keep it under 50C if you can.
     
  6. exponential

    Gangster

    Joined: 31 Oct 2004

    Posts: 149

    Be carefull with a multimeter, if you short the wrong thing with a live motherboard, their wont be any volts left to monitor
     
  7. fragster

    Gangster

    Joined: 5 Dec 2003

    Posts: 307

    Location: Essex

    I'm also at 2.5ghz, stock voltage. Though CPUz and Asus Probe reports the core voltage at 1.488v

    strange.

    I wouldn't worry so much about the voltage, just keep an eye on the temps :)