Phenom II 940 BE Voltage Question.

SCFAdamVcG · May 30, 2009

Hi there,I was wondering how is the cpu's recommended max voltage calculated by amd?
is it calulated by the temperatures?
The best to you all,Thanks . Adam.

QuietIce · May 31, 2009

Official recommendations mean very little when OC'ing. After all, you've exceeded the "official recommendations" the second you over-clock the chip ...

solstice · May 31, 2009

My guess is that the max operating voltage has to do with reliability of the device given expected life time say 10 years. If you over stress the voltage, you may potentially get early failure of the device. The tricky question is how much margin do one have when trying to over volt? In my limited experience of overclocking CPUS, I only have one processor that eventually gave me a functional error when over volt. Basically, the CPU said machine check sum error. I searched on the web at the time. Basically, this means there are computation error in the results. I replaced the system. That CPU lasted only a year to 2 or so. The funny thing is that I over volt not because I was overlcokcing but because I wanted to use a socket Pentium III processor in a slot. That forced a 0.18um processor to see 2V supply. I am sure I accidetentally over volt it even higher since I was not very careful.

So yes, over volt => shorter life. Just a matter of when.

SCFAdamVcG · May 31, 2009

ok,thanks for the reply

how long do you think it'd last at around 35-45c with a load with 1.55 volts?
i noticed that overclocking with the ht reference clock didnt help anything and the chip seems to want about 5 increments up in voltage to even boot into windows,last night i had it @ 3.8ghz on multiplier but also tried the ht reference clock overclock,could it be multiplier that needs all this voltage?

SCFAdamVcG · May 31, 2009

oh also,i did take off a single radiator off my water cooling system because i didnt need it at the time,if the temps start to get above 50 then i'll be putting that 2nd radiator back on..hopefully it'll help,hot summer making it high i think.

solstice · May 31, 2009

1.55V and still get 35 to 45C? That is one mighty water cooling systems. Is this CPU core temp? I could never reach 1.45V and above because my cooling system is in sufficient. Can you post your setup?

It is only about 14.8% larger than the 1.35 max core voltage for the CPU. Quiet a few people have used 1.42V and seem to lasts at least as long as PII came out. That would be early 6 months now. My guess is CPU should run for about 1 year to two years. I basically used 10 years * exp^(-1.14) = 3 years since most things dies in exponential fashion.

This assumes that the voltage would not give a sudden death of course. At 1.55V is pretty save from that sudden death.

SCFAdamVcG · May 31, 2009

ok,here's my setup -

[CPU] AMD Phenom II 940 Black Edition Socket AM2+ ~3.7ghz@ 1.51 volts
[Motherboard] MSI-DKA790GX With bios version 1.7
[Cooling]Bigwater 745 [Thermaltake]
[Gfx] Radeon HD4870 GDDR5 1GB
[Cooling paste] Artic silver
2x 80mm fans
Any other information you are needing btw?

solstice · May 31, 2009

Nice, this seem pretty cheap water cooling system. Hmm, I will definitely think about this as a next upgrade.

rayik · Jun 1, 2009

SCFAdamVcG said:
ok,here's my setup -

[CPU] AMD Phenom II 940 Black Edition Socket AM2+ ~3.7ghz@ 1.51 volts
[Motherboard] MSI-DKA790GX With bios version 1.7
[Cooling]Bigwater 745 [Thermaltake]
[Gfx] Radeon HD4870 GDDR5 1GB
[Cooling paste] Artic silver
2x 80mm fans
Any other information you are needing btw?

Why are you running such high voltage. My 940 BE does 3500 on stock voltage of 1.35. Try turning your voltage down. If you have to go to 3500 or 3600, there really is no real world performance difference than 3700.

QuietIce · Jun 1, 2009

rayik said:
Why are you running such high voltage. My 940 BE does 3500 on stock voltage of 1.35. Try turning your voltage down. If you have to go to 3500 or 3600, there really is no real world performance difference than 3700.

Crunching or Folding will show performance differences over 200 MHz. It may mean nothing for games or common tasks but distributed computing is another thing entirely!

BTW, you can delete your own post - just look for the "Delete" button under "Edit" ...

SCFAdamVcG · Jun 1, 2009

who? me or him lol

btw it got to 55c with 1.7 volts..accidentally incremented because i turned the vdd to auto..wierd bios,i'll get round to posting screenshots when i can get a camera.

cdawall · Jun 1, 2009

SCFAdamVcG said:
ok,here's my setup -

[CPU] AMD Phenom II 940 Black Edition Socket AM2+ ~3.7ghz@ 1.51 volts
[Motherboard] MSI-DKA790GX With bios version 1.7
[Cooling]Bigwater 745 [Thermaltake]
[Gfx] Radeon HD4870 GDDR5 1GB
[Cooling paste] Artic silver
2x 80mm fans
Any other information you are needing btw?

not the best watercooler set ups but enough for what you are running 1.51v is just fine AMD actually specs the chips all the way up to 1.55v in the white papers of it

rayik said:
Why are you running such high voltage. My 940 BE does 3500 on stock voltage of 1.35. Try turning your voltage down. If you have to go to 3500 or 3600, there really is no real world performance difference than 3700.

and my 955 does 3.7ghz on stock volts are you trying to start an argument cause other than that your post is pointless.

3.5-3.7ghz can show a performance difference depending on the application thats a good couple minutes when rendering 3D and a couple of FPS when playing games

Dapman02 · Jun 1, 2009

solstice said:
1.55V and still get 35 to 45C? That is one mighty water cooling systems. Is this CPU core temp? I could never reach 1.45V and above because my cooling system is in sufficient. Can you post your setup?

It is only about 14.8% larger than the 1.35 max core voltage for the CPU. Quiet a few people have used 1.42V and seem to lasts at least as long as PII came out. That would be early 6 months now. My guess is CPU should run for about 1 year to two years. I basically used 10 years * exp^(-1.14) = 3 years since most things dies in exponential fashion.

This assumes that the voltage would not give a sudden death of course. At 1.55V is pretty save from that sudden death.

I run [email protected] at full 12 hour load my cpu never goes over 43 degrees. I of course have some pretty beefy componants, but it is none-the-less sweet.

SCFAdamVcG · Jun 2, 2009

ok,and how long will the chip last for @ those voltages?
im confused beetween what coretemp reads as vid and what cpu-z reads as core voltage..
no matter how high i set the vdd i cant boot windows at 3.8-3.9ghz without adding core voltage.

QuietIce · Jun 2, 2009

CoreTemp simply shows the BIOS setting, not the voltage being delivered ...

cdawall · Jun 2, 2009

SCFAdamVcG said:
ok,and how long will the chip last for @ those voltages?
im confused beetween what coretemp reads as vid and what cpu-z reads as core voltage..
no matter how high i set the vdd i cant boot windows at 3.8-3.9ghz without adding core voltage.

well considering AMD itself has spec'd these chips to run at 1.55v i would imagine that they wont have any issues with lifespan running at those voltages

SCFAdamVcG · Jun 2, 2009

how do i delete this topic?

QuietIce · Jun 2, 2009

Why would you want to do that ...?

Bobnova · Jun 2, 2009

QuietIce said:
Crunching or Folding will show performance differences over 200 MHz. It may mean nothing for games or common tasks but distributed computing is another thing entirely!

BTW, you can delete your own post - just look for the "Delete" button under "Edit" ...

Hell folding@home shows even a 100mhz overclock for me, it makes a distinct difference.

I suspect that if i tested correctly (not playing music or browsing or anything) it'd show a difference of 50mhz.

Beyond that, i suspect you'd be hard pressed to tell the difference between 3.2 and 3.7, really.

QuietIce · Jun 2, 2009

Bobnova said:
Beyond that, i suspect you'd be hard pressed to tell the difference between 3.2 and 3.7, really.

I think any program that runs the CPU hard (video encoding as another example) will show a marked difference with higher CPU speeds.

That said, a lot of people, unless they're playing intense games, will never use all of their CPU. I'm still typing on my old Opty 180 sig rig - while running SETI. I can watch movies, surf, play music, even do music editing and encoding without a hitch while SETI is quietly crunching away in the background. Newer games sometimes give me problems but older ones don't. If it weren't for SETI and a new game my son-in-law wants me to get into I'd probably run this system for another two years ...

Phenom II 940 BE Voltage Question.

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