Overclocking voltage help - vdroop?

[clidx]

i'm comfortably running at 3.3ghz, 7hrs stable on P95 but the voltage is bothering me. in my bios it's showing as 1.3625 but in cpu-z, when all 4 cores are stressed it's at 1.32? i read that there's something called vdroop that drops the vcore when idle. is this so or is cpu-z showing the incorrect info?

thanks.

[puntoMX]

... in my bios it's showing as 1.3625 but in cpu-z, when all 4 cores are stressed it's at 1.32? i read that there's something called vdroop that drops the vcore when idle. is this so or is cpu-z showing the incorrect info?

It´s showing you the correct info, the voltage drops a little under load too compared to it when idle and on 3.33GHz. Play a little with it and you will see what I’m talking about.

[clidx]

Ok, thanks for the information I read about a vdroop-preventing pencil mod for my board (p5b deluxe) and I tried it and lowered the vcore to 1.325V in the bios and it passed 3 hours, 4 cores P95 with small ffts. and cpu-z showed it as 1.32V, again. turns out that the p5b deluxe is a big vdrooper (is that even a word...)

so thanks for the help. i'm now just wondering why asus made the vcore settings in the bios, in such small increments but drift so far from them in real world use...

[midi2k6]

I advise not to manual OVERCLOCK your system if you don't know overclocks because mostly not just your hardwares, you need good PSU.

Usually newest motherboard factory comes with the software for overclocking automatically sets voltages on your hardwares in BIOS.

Careful! Don't burn your power supply (i would recommend using 550W PSU ~ higher)

[bonestonne]

not necessarily a 550W power supply..that does nothing if its not quality. 430+W power supply is fine, but it would need to be 80% or more certified [meaning at any given time its producing 80% of its rated wattage].

[puntoMX]

Okay, wait a minute here...

Those voltage drops are normal, and not caused by the PSU; it’s the motherboard that drops voltage when more Amperes are drawn.

You guys really think a 12(v)*18(A) =216W PSU can’t pull a 65, 85 or 90W TDP CPU? My CPU, a E2180, at maxed out load doesn’t eat up more then 40W

This Leaving enough power to the VGA card (planning on an 8800GT/GTX or the new ATi line when it comes out soon), let’s say a 120W max.

HDD´s (each max 12W, but that’s not only on the 12V line) and a DVD-RW.

The fans are using almost nothing (2.16W each for mine at full speed).

So, my system uses about 180W on the 12V line max!

[clidx]

the only reason i set the voltages manually is that on auto, the mobo was a bit too.. let's say generous on the voltage settings. i could get a good 0.5V lower by setting it manuall (note i have not included vdroop in this calculation )

and i think my psu will be enough for the time being. after putting ALL of my hardware into account, it recommends me a 325W psu. i can post what i put in if you like.

or we can do it manually. 95W tdp on 12V, X1950 Pro, ~66W (according to reviews), 95+66=151W so far. hdd*2=24W (according to puntomx and let's assume 12V) so 175W. and i don't know how much power a dvd burner uses so i'll assume 12W like a hdd. 24+175=299W. my psu has 2 12v rails of 15A each so i'll assume 30A (but i'm probably wrong in seeing it like this), so 12V*30A=360W. i'm safe by 61W and that's putting everything on the 12V rail. and this is the ABSOLUTE maximum unless usb devices suck the 12V rail (and i think they run on the 5V rail though i could be wrong).

of course, puntomx did most of the calculations.. just proving my psu is enough

Edited November 20, 2007 by clidx

[Zxian]

@clidx - You're drawing more than 200W on that system, especially with the X1950Pro and the overclock that you've got. My system at home (see this post for specs) draws about 250W at full load. Since your overclock is higher than mine and you've got a more powerful video card, I'd say that you're using about 300W (your calculations were wrong ... 24+175 != 299... but you got the right number). Your seasonic PSU should be able to handle that load well enough. Seasonic's are generally made from high quality components and don't crap on you.

[puntoMX]

95W tdp on 12V, X1950 Pro, ~66W (according to reviews), 95+66=151W so far. hdd*2=24W (according to puntomx and let's assume 12V) so 175W. and i don't know how much power a dvd burner uses so i'll assume 12W like a hdd. 24+175=299W. my psu has 2 12v rails of 15A each so i'll assume 30A (but i'm probably wrong in seeing it like this), so 12V*30A=360W. i'm safe by 61W and that's putting everything on the 12V rail. and this is the ABSOLUTE maximum unless usb devices suck the 12V rail (and i think they run on the 5V rail though i could be wrong).

That CPU has a TDP of 95W, but will be more likely using 65W (load) on stock voltage, your Video card will draw some 124W (load) (as I remember well), and each HDD some 15Watts (seek), but not al will be taken from the 12V line...

Just to get you on the right track here .

By the way, you can´t add those 2 12V lines together like that...

[clidx]

i thought i couldn't add the 12V rails together like that (as i said in my other post) but i couldn't think of any other way to combine them to do the maths.

@zxian thanks for the info, now i don't need to worry about my friends nagging me that you need a 500W psu when overclocking... *ahem* noobs.

thanks to all of you. now i don't need to worry about my friends or midi2k6s warning unless i add more hardware.. and even then i doubt i'll be using up 61W easily..