windows versus bios voltage

vishal · 26 Jan 2006 at 19:22

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

twiceborn · 26 Jan 2006 at 23:29

vishal said:
what is the real voltage to believe?

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

vishal · 28 Jan 2006 at 08:05

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.

NightSt@lk3r · 28 Jan 2006 at 08:10

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

twiceborn · 30 Jan 2006 at 23:09

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

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.

exponential · 31 Jan 2006 at 03:15

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

fragster · 31 Jan 2006 at 12:17

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