Overclock.net › Forums › AMD › AMD CPUs › Fx 8350 needs 1.40 volts for 4.5 ghz , but to get 4.7 ghz I need to give 1.48-1.50 voltages. why ?
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Fx 8350 needs 1.40 volts for 4.5 ghz , but to get 4.7 ghz I need to give 1.48-1.50 voltages. why ? - Page 2

post #11 of 18
Thread Starter 
Quote:
Originally Posted by MrLinky View Post

Not to nitpick, but the term voltage wall describes a situation where adding more voltage to an overclock doesn't increase stability or OC headroom. Your post described the law of diminishing returns, which, in this case, is expressed as the exponential increase of required voltage to achieve the next linear step in clock speed. smile.gif

kersoz2003: The "sweet spot" is subjective for everyone. I would agree with MrTOOSHORT that 4.6 GHz is a respectable number, but in the end I would say it depends on your needs and how long you plan on keeping this CPU. If you plan on keeping your current setup for two or more years, stick with 4.6 GHz. If not, squeeze every MHz possible out of it. biggrin.gif

It should also be noted that a lot of FX cpus need excessive amounts of voltage to run Prime95 (mine being one of them). My overclock is stable in IBT and I have yet to crash or error out in real-world applications (gaming, video encoding, encryption and everything in between). It might be worth it to see what voltage is enough for 4.7 GHz in IBT.

I will also try IBT. thanks for the info smile.gif I guess for 4.7 ghz prime 95 requires far way voltage than the real world usage . So after testing 4.6 ghz .I will also test 4.7 ghz with 1.46-.1. 47 voltages in IBT wink.gif

Prime 95 tests finished and my results :

4.7 ghz @ 1.50-1.52 volts = 72 degress

4.6 ghz @ 1.44-1.46 volts = 62 degress

4.5 ghz @ 1.40-1.41 ghz = 52 degrees

So 4.6 is my choice smile.gif which 62 degrees is adviced from AMD for fx 8350

maybe as you said IBT will provide better ( less volts-less heat) results for me. I will try with it with lower volts all of these above
Edited by kersoz2003 - 9/29/13 at 5:38pm
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post #12 of 18
Thread Starter 
Quote:
Originally Posted by MrLinky View Post

Not to nitpick, but the term voltage wall describes a situation where adding more voltage to an overclock doesn't increase stability or OC headroom. Your post described the law of diminishing returns, which, in this case, is expressed as the exponential increase of required voltage to achieve the next linear step in clock speed. smile.gif

kersoz2003: The "sweet spot" is subjective for everyone. I would agree with MrTOOSHORT that 4.6 GHz is a respectable number, but in the end I would say it depends on your needs and how long you plan on keeping this CPU. If you plan on keeping your current setup for two or more years, stick with 4.6 GHz. If not, squeeze every MHz possible out of it. biggrin.gif

It should also be noted that a lot of FX cpus need excessive amounts of voltage to run Prime95 (mine being one of them). My overclock is stable in IBT and I have yet to crash or error out in real-world applications (gaming, video encoding, encryption and everything in between). It might be worth it to see what voltage is enough for 4.7 GHz in IBT.

As you said IBT requires less voltage and says stable smile.gif why ? Can I trust ITB and 10 sets of standart or high ? or how much is enough ? I will retest tomorrow now I have to sleep smile.gif
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post #13 of 18
Quote:
Originally Posted by MrLinky View Post

Not to nitpick, but the term voltage wall describes a situation where adding more voltage to an overclock doesn't increase stability or OC headroom. Your post described the law of diminishing returns, which, in this case, is expressed as the exponential increase of required voltage to achieve the next linear step in clock speed. smile.gif

kersoz2003: The "sweet spot" is subjective for everyone. I would agree with MrTOOSHORT that 4.6 GHz is a respectable number, but in the end I would say it depends on your needs and how long you plan on keeping this CPU. If you plan on keeping your current setup for two or more years, stick with 4.6 GHz. If not, squeeze every MHz possible out of it. biggrin.gif

It should also be noted that a lot of FX cpus need excessive amounts of voltage to run Prime95 (mine being one of them). My overclock is stable in IBT and I have yet to crash or error out in real-world applications (gaming, video encoding, encryption and everything in between). It might be worth it to see what voltage is enough for 4.7 GHz in IBT.

Little bit nit picky IMO - Just describing it in my own words - I guess there's a definition for everything with you geeks though rolleyes.gif
post #14 of 18
Quote:
Originally Posted by kersoz2003 View Post

As you said IBT requires less voltage and says stable smile.gif why ? Can I trust ITB and 10 sets of standart or high ? or how much is enough ? I will retest tomorrow now I have to sleep smile.gif

Linpack-based tests, like IBT, use the FPU to do floating point calculations. In addition to Floating Point calculations, Prime95 also does other types of calculations which use different parts of the CPU. My best guess is Prime95 stresses a weak area that IBT (and seemly most real-world programs) don't touch.

Use 5 sets on Standard to quickly ballpark the minimum voltage necessary, then use 10 or 20 sets on High to test for stability. A word of caution though: IBT will use more power and run your CPU hotter than Prime95 will, so keep an eye on those core temps.
     
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post #15 of 18
Quote:
Originally Posted by HairyGamer View Post

Little bit nit picky IMO - Just describing it in my own words - I guess there's a definition for everything with you geeks though rolleyes.gif

tongue.gif


Edited by MrLinky - 9/29/13 at 9:44pm
     
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post #16 of 18
Most my friends have 8350s just like I do now.

4.6-4.8ghz seems to be the sweet spot needing 1.43-1.48V from what iv seen of overclocking there chips for them.
Earlier chips being the better ones. Mine does 5ghz on 1.48V but I just run 4.75ghz with 1.43V.
Probably because they started binning the better chips for the FX 9XXX with the newer ones.

If your just multiplyer overclocking drop that back down and start pushing the FSB and north bridge.
The difference between a pure multi and fsb overclock on mine is .10 points on cinebench at the expense of needing to use a little more cpu-nb voltage and 4C hotter temps.
post #17 of 18
Quote:
Originally Posted by bmgjet View Post

Most my friends have 8350s just like I do now.

4.6-4.8ghz seems to be the sweet spot needing 1.43-1.48V from what iv seen of overclocking there chips for them.
Earlier chips being the better ones. Mine does 5ghz on 1.48V but I just run 4.75ghz with 1.43V.
Probably because they started binning the better chips for the FX 9XXX with the newer ones.

If your just multiplyer overclocking drop that back down and start pushing the FSB and north bridge.
The difference between a pure multi and fsb overclock on mine is .10 points on cinebench at the expense of needing to use a little more cpu-nb voltage and 4C hotter temps.

I would love to get a look at your 8350 oc bios settings.
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post #18 of 18
Nothing special.
Just 1.42V cpu high llc
1.3V cpu-nb normal llc

215fsb
22X multi

2.8ghzHT
2.4ghzNB

2ghz Ram
1.65V

Release day chip in a sabertooth 2.0 cooled with antec 920 that has been lapped. Extra fan blowing on socket and VRM area.
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  • Fx 8350 needs 1.40 volts for 4.5 ghz , but to get 4.7 ghz I need to give 1.48-1.50 voltages. why ?
Overclock.net › Forums › AMD › AMD CPUs › Fx 8350 needs 1.40 volts for 4.5 ghz , but to get 4.7 ghz I need to give 1.48-1.50 voltages. why ?