Hello,
What do people consider safe for a 3.3v rail to be running at? I gather that its hard to get an accurate reading, but readings from bios and hardware monitors are what I use. Of course under bios its not under any load even if it might be more accurate.
Also what does it power?
Regards,
Speed
http://www.formfactors.org/developer...20PSDG2.01.pdf
Some light reading for you
Or, trust somebody who has read that before - 5% tolerance.
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3.3v is for the PCI bus mainly
as for voltage ranges, -/+0.1v should be okish, though 3.3v is one of those rails that shouldn't fluxuate much, what psu do you have?
I would tend to trust BIOS readings for voltages. Hardware monitors work too so long as acpi isn't being funny
Last edited by aidanjt; 30-01-2005 at 08:14 PM.
BIOS uses the same chips to monitor temps and voltages as any program. If a BIOS is out of date or buggy it might report the wrong readings. :\Originally Posted by aidanjt
Multimeter is the best way to check.
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Multimeter is definatly the best way to check.
3.3 rail really needs to be above 3.1 but there shouldnt be any problems on the other side, many people have vsense modded the 3.3rail upto 3.6 or even 4v.
Mine sits nicely at 3.3v, exactly, with a vsense mod
Kez, correct, but ACPI is the interface the programs use, so if its glitchy, then the env. monitoring programs spew out crap. thats why you can often get different readings between the BIOS and programs.
But yes, a Multimeter is definatly the most accurate way of checking.
Hello,
Thanks everyone for their replies and information. To answer aidanjt's question I have a Tagan 480W PSU.
I've checked in both bios and my hardware monitor and the voltages seem to be quite similar. The main reason I asked about 3.3v is that is the rail I've always noticed it to be low. Its strange really, I've changed the PSU and the motherboard recently and after a week or two its still quite low, although not as low as it has been before the changes. Maybe I've had two bust PSU's in a row or something.
My current 3.3v is around 3.02 to 3.05 and thats at idle/web browsing etc.
Using CPU Burn-in and of course the hard ware monitor it can go as low as 2.75. 5v and 12v stay above there numbers while under this heavy load.
Is it possible a certain device is sucking a strangely high amount of power under load off the 3.3v rail?
I'm not overclocking or anything, all stock speeds.
Whats this vsense mod you are on about? I'll google it but it would still be nice for someone to explain it!
Regards
Speed
Last edited by Speed; 30-01-2005 at 09:53 PM.
Check it with a multimeter to be sure of the voltages if you can.
Vsense modding is a way of altering the voltage on a rail, but it requires use of a soldering iron and a couple of other components.
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I take it checking with the multimeter means starting the psu up outside of the case (I know how to do that). Then using multimeter select the correct mode and touch the two probs onto the correct output? Or the Correct output to ground?
I only ask as I've never done it before.
Yeah I worked out what vsense modding was thanks. Might end up buying a PSU with adjustable pots at this rate.
Speed
Last edited by Speed; 30-01-2005 at 10:17 PM.
Nope, start the pc as normal - if theres no load it might give 3.3v, which would make the test pointless..
Poke the red probe in the orange pin of the aux connector if you psu has one.. ifnot..should be easy enough to poke down the atx connector on an orange pin..
Set the meter to 20vDC. make sure you connect the probes to the right place on themultuimeter (not the 10A hole!) so you dont short the psu.
Adjustable pots means taking the lid off the psu.. not that its difficult..pots in psu's arnt always there for fiddling with
Vsense modding is not difficult. It can be done without any soldering, and is probably the lowest risk v mod you could ever do.. (as theres no small chips to solder to..).
Last edited by SilentDeath; 30-01-2005 at 10:55 PM.
Right, thanks for the information. I'm aware of how to adjust pots, but I'm pretty sure my psu doesn't have any adjustable pots.
You say there is a way to do it without soldering. Any guides you know of that don't use soldering?
Thanks
Speed
Is it soldering that you dont want to do, or the vsense mod in general?
I meant that as theres no very small pins to solder to.. you could quite easy follow the same guides without having to solder.. but it is basicly the same mod... soldering would be the better way to do it though...
iirc for each rail, you need just one resistor and one pot, so its not something thats going to be hard to solder..
Hmm.. I have a Tagen PSU too, as far as I'm concerned they are probibly the best money can buy, especially in terms of stability even with handling overclocks.
The only other limiting factor i can imagine is the motherboard itself, small tracks, or low quality mosfits might be the cause.
Well it seems I may not need any mods after all. I've currently got the multimeter attached to the ATX connector with the pc running. The hardware monitor now says 3.33v. So maybe the multimeter probes have pushed pins to make a better connection or something. I did check the pins before all this and it didn't effect anything.
God why is nothing straight forward. The muiltmeter is reading a healthy 3.41v under idle. Under full load (cpu burn-in) the hardware monitor reads 3.07v ish and the muiltmeter reads 3.20v-3.23v.
On a side note anyone know where to download Prime95? Has it been discontinued or something as I googled it with not much luck.
Speed
Prime95 - http://mersenne.org/gimps/p95v238.exe
Your voltages look OK
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