AMD 45nm median voltage limits:

Some theoretical voltage limits:


Thuban (6 core) *
- 24/7 voltage = 1.475-1.52v
- benchmarking voltage = 1.55v
- suicide voltage = 1.575v
- unsafe voltage, will degrade = 1.6v+

Deneb (4 core)*
- 24/7 voltage = 1.50-1.55v
- benchmarking voltage = 1.55-1.60v
- suicide voltage = 1.625v
- unsafe voltage, will degrade = 1.65-1.7v+

Heka (3 core)*
- 24/7 voltage = 1.50v-1.55v
- benchmarking voltage = 1.55v-1.60v
- suicide voltage = 1.625v
- unsafe voltage, will degrade = 1.65-1.7v+

Callisto (2 core)*
- 24/7 voltage = 1.50v-1.55v
- benchmarking voltage = 1.55v-1.60v
- suicide voltage = 1.625v
- unsafe voltage, will degrade = 1.65v-1.70v+

Regor (2 core Athlon II)*
- 24/7 voltage = 1.50v-1.55v
- benchmarking voltage = 1.55-1.60v
- suicide voltage = 1.60v-1.625v
- unsafe voltage, will degrade = 1.625-1.675v +

Propus (4 core Athlon II)*
- 24/7 voltage = 1.50-1.55v
- benchmarking voltage = 1.55-1.60v
- suicide voltage = 1.60-1.625v
- unsafe voltage, will degrade = 1.625-1.675v+

* Voltages moderately safe when CPU temperature is under 55-60c 100% load.

This is lovely!

If my Deneb need 1,48 volts @ 4ghz but I read 1,45 volts in Cpu-Z (Voltage drop).

Do I consider the real voltage as 1.48 or 1,45?

1.48?

Quote:

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Originally Posted by Mavhenz

This is lovely!

If my Deneb need 1,48 volts @ 4ghz but I read 1,45 volts in Cpu-Z (Voltage drop).

Do I consider the real voltage as 1.48 or 1,45?

1.48?

---

Yep the idea just popped into my head a while ago.

Consider what CPU-Z says. :)

Very good BeepBeep2, many will thank you this summary ;)

It sounds really weird that there's only a 0.1V delta between "24/7 safe" and "will degrade, totally unsafe"

You cant always go by what your bios or cpuz tells you.
I have a 955c3 that runs at 1.5v 4ghz on 2 boards(Biostar TA785G3 and BFI 790gx M3H5) while on a third (MSI 760GM-E51) it uses 1.42v at 4ghz.
This of course is a lie as the thermal output at 1.42c is the same as the boards running 1.5v. If I use 1.5v on the later board(MSI) for 4ghz the heat produced far excedes that of 1.5v on my other 2 boards.
Same .08v variation applies to all clocks as reported by bios and cpuz at stable voltages/clocks.

Deneb 24/7 voltage 1.575V? I sincerly hope that is a typo. 1.5-1.525V sounds a lot more suitable to me. I'd say 1.5V for C3 revision, 1.525V for C2 revision.

Quote:

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Originally Posted by Zeus

Deneb 24/7 voltage 1.575V? I sincerly hope that is a typo. 1.5-1.525V sounds a lot more suitable to me. I'd say 1.5V for C3 revision, 1.525V for C2 revision.

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Really? I was thinking the opposite but those voltages seem about right to me. My C2 gains until 1.5V then after that it is pointless... so that seems to roughly match my findings. Although I am on an M4A79T Deluxe Random Vcore Generator Edition..

It depends on whether the chip tolerates the voltage or not. Some chips like voltage where others don't. From what i've seen C2 is a little more voltage intolerant beyond certain values than C3 but seemed to need a tad more.

The OP states "with good air or watercooling". Since "good" is highly debatable, it's better to put the ballpark number a tad or two lower. I for one never go over 1.48V for 24/7 operation, despite good watercooling.

I wouldn't go any higher for 24/7 then 1.53v with good cooling. 1.47v seems like a real sweet spot for my chip. I'm now convinced that my ram is the only thing that's stopping me from 4.2ghz.

Quote:

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Originally Posted by Zeus

Deneb 24/7 voltage 1.575V? I sincerly hope that is a typo. 1.5-1.525V sounds a lot more suitable to me. I'd say 1.5V for C3 revision, 1.525V for C2 revision.

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Well gotvoltage has been running is 555BE @ 4.1 on 1.625v for four months without degradation...

I've been running...1.575v for half a year.

Both are C3. It's pretty safe.

i think you need to add a little footnote with something like *these safe voltages only apply to CPUs that are kept under ~60C
since we know how temperature sensitive they are with stability

Quote:

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Originally Posted by Manicdan

i think you need to add a little footnote with something like *these safe voltages only apply to CPUs that are kept under ~60C
since we know how temperature sensitive they are with stability

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+1 thanks


EDIT: List tweaked, keep commenting, I'll change it.

Quote:

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Originally Posted by BeepBeep2

+1 thanks


EDIT: List tweaked, keep commenting, I'll change it.

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perfect, cause for me running my cpu off the stock heatsink using a resistor to run the fan at about 2000rpms, makes the safe 24/7 voltage about 1.35, lol. its about the lowest extreme cooling ever.

It's much more simple than that. AMD stated that 1.55V was the maximum that their 45nm SOI process should be subjected to. It hardly matters which core you've got. 1.55V should be safe provided the silicon is kept in check thermally (at or below 62C) and 1.55V is what your board is actually giving it. Load line calibration can cause major spikes, so it's worth being mindful of that. Numbers above that are just speculation. Numbers below that are just preference.

Quote:

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Originally Posted by Particle

It's much more simple than that. AMD stated that 1.55V was the maximum that their 45nm SOI process should be subjected to. It hardly matters which core you've got. 1.55V should be safe provided the silicon is kept in check thermally (at or below 62C) and 1.55V is what your board is actually giving it. Load line calibration can cause major spikes, so it's worth being mindful of that. Numbers above that are just speculation. Numbers below that are just preference.

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That was for the AM2 Phenom II 940.

I mean, yes that's true but chew has already seen degradation of Thuban around 1.52v.

That's partially why I've changed the chart so all non-Thuban CPU's are 1.55v for 24/7.

I guess I shouldn't be running my Thuban with 1.62v with 23/7 load :lol:

Eh, if it dies, it dies....it's served its purpose :shrug:

nice, what mhz?

Quote:

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Originally Posted by BeepBeep2

That was for the AM2 Phenom II 940.

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That's pretty much the entire point I was making. That doesn't just apply to one core. It's valid for all cores made on that process unless the process itself changes. It might have been tweaked over time, but I haven't seen any evidence suggesting there there has been a modification causing a significant change in maximum safe voltage.

I always take claims of "degradation" with a mountain of salt. While I know the intentions are always good, informing others of where a CPU is physically damaged, it's very difficult to objectively isolate. It's just speculation.

Quote:

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Originally Posted by Particle

That's pretty much the entire point I was making. That doesn't just apply to one core. It's valid for all cores made on that process unless the process itself changes. It might have been tweaked over time, but I haven't seen any evidence suggesting there there has been a modification causing a significant change in maximum safe voltage.

I always take claims of "degradation" with a mountain of salt. While I know the intentions are always good, informing others of where a CPU is physically damaged, it's very difficult to objectively isolate. It's just speculation.

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I believe a slight change in process did happen Thuban uses a low K dielectric layer now and Deneb did not.

I run 1.57 24/7

Quote:

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Originally Posted by demonkevy666

I believe a slight change in process did happen Thuban uses a low K dielectric layer now and Deneb did not.

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Sure, but it would be incorrect for any of us to just assume that means less voltage is safe. We need to either establish that through testing with many samples (like our overclocking tracker threads) or get it from an authoritative source on the subject like an actual engineer. Until then, the proper course of action is to assume business is as usual with extra caution being an optional, personal preference.

In terms of how that applies here, I don't want those who don't know much about what voltages are safe to reference this information and perhaps limit their results below where they could have been because they were afraid of using a higher voltage that was probably still just fine/safe. Overclockers are already generally aware that there is risk involved, even more certainly so if they're referencing information about what voltages are "safe" to use. For this audience, I think conservatism should be a note rather than the primarily advertised information.

maybe u can add average OC potencial for chips, good work. We can waiting for great correct from master Chew :)

there are variables that you have not taken into consideration. different lots (batches), wafers, and dies can have different characteristics. also there are inter-die variations. engineers at amd must deal with these factors. they have to have a reliable product but performance is still important. maybe they could help overclockers out some more by giving some guidelines.

Quote:

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Originally Posted by Particle

That's pretty much the entire point I was making. That doesn't just apply to one core. It's valid for all cores made on that process unless the process itself changes. It might have been tweaked over time, but I haven't seen any evidence suggesting there there has been a modification causing a significant change in maximum safe voltage.

I always take claims of "degradation" with a mountain of salt. While I know the intentions are always good, informing others of where a CPU is physically damaged, it's very difficult to objectively isolate. It's just speculation.

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Adding of the low-k dielectric layer changed things up quite a bit for Thuban.

chew* advised staying under 1.52v with Thuban because he was seeing chips degrading...

But thats all part of why I started this thread...to find out this stuff. Not to state it. :)

I just use what voltage is needed until it stops scaling. :p: It's not like I plan on keeping a CPU forever anyway.

1.475 is max i would bother with most chips for 24/7. TBH if I had the time and ripped my rig apart and put the amd system in thats been waiting for quite some time, I would be happy with 3.6 24/7, then again my 24/7 pc is mission critical, Quiet and cool.

The point at which is takes excessive voltage for minimal gains for 24/7 use is the point that you will degrade varies chip to chip but 1.475 is preety much safe for all chips.

Best way to find out is to remove the buffer (IHS) run on cool water at a max prime stable speed.

Let water get room temps then boot. It will instapop the chip ;) think that happened at 1.5v IIRC but not 1.475 with quite a few test candidates.

If you can instapop, then it's fairly safe to assume you can degrade with the buffer in place.

Quote:

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Originally Posted by chew*

1.475 is max i would bother with most chips for 24/7.

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interesting...

Updated chart, don't know if it's much better.

I started this thread to help avoid people going "I put 1.70v on my Phenom and it still fails prime whats wrong"

Quote:

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Originally Posted by BeepBeep2

interesting...

Updated chart, don't know if it's much better.

I started this thread to help avoid people going "I put 1.70v on my Phenom and it still fails prime whats wrong"

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Then they need more vcore, clearly.

:ROTF:

Looking good

great!

Nice to hear thubans can do 1.5 vcore for 24/7. I was reading there website so I tried stay under 1.4 vcore. I was going post question the CPU-NB core voltage. Does this apply for CPU-NB core? NB voltage start at 1.15 vcore I was wondering increasing them to 1.4 is too much?

Quote:

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Originally Posted by panzerchaos47

Nice to hear thubans can do 1.5 vcore for 24/7. I was reading there website so I tried stay under 1.4 vcore. I was going post question the CPU-NB core voltage. Does this apply for CPU-NB core? NB voltage start at 1.15 vcore I was wondering increasing them to 1.4 is too much?

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I'd stay under 1.4v for 24/7, I could later update this thread to include CPU/NB voltages but that can wait. :D

I shoved 1.55v into my Deneb's CPU_NB once for SuperPi 1M and it doesn't appear degraded but thats stongly ill-advised.

Id like to hear more from people who have actually degraded any of these chips under "normal";) overclocking.
Ive had a 7 year old Athlon64 running at 1.65v for 1 year full load 24/7 on stock cooler with no issues. I know not same processes.:rolleyes:
Along with a Athlon 620 at 1.55v and 955c3 at 1.5v 24/7 full load for 1.5 months and ran those volts for 6 months prior both under 55c.
Then I have a Thuban at 1.52v at ~45c full load 24/7 last 1.5 months. As of yet I havent seen any I'll affects on any cpu Ive ever owned.:shrug:
So lets hear some horror storys:eek:

Added: btw I like what you got going on here Beep sub'd:up: and I'll be looking forward to hearing more about the NB voltages:yepp:

i ran my 945BE (RB-C1) at 1.67-1.72v 24/7 on water for months and never ran into degradation had it buzzing at 4ghz way before most people could get that high (chew* excluded obviously)

my current 1090T is pretty happy at 1.5625v (1013CPMW stepping) but with vdroop thats only like 1.475ish from meter readings on the CH3 benchmarking over that i haven't seen improvements on tec/air with phase 1.6v is about the max i saw scaling on

I ran 1.63v for months on water and previously on air for months. Recently I started crashing, but I was on the ragged edge of 24/7 stability and ambient temps have increased greatly. I don't want to say it HASN'T degraded, but I doubt it.

Quote:

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Originally Posted by chew*

Best way to find out is to remove the buffer (IHS) run on cool water at a max prime stable speed.

Let water get room temps then boot. It will instapop the chip ;) think that happened at 1.5v IIRC but not 1.475 with quite a few test candidates.

If you can instapop, then it's fairly safe to assume you can degrade with the buffer in place.

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What do you mean by "instapop"?

Quote:

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Originally Posted by afireinside

I ran 1.63v for months on water and previously on air for months. Recently I started crashing, but I was on the ragged edge of 24/7 stability and ambient temps have increased greatly. I don't want to say it HASN'T degraded, but I doubt it.



What do you mean by "instapop"?

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The chip goes "pop" and dies...metaphorically speaking...

Well as much as I didn't want to admit it... 1.6v+ for extended periods of time (5 months on water, no idea how many on air when I first got it) has damaged my 940BE. Needs increased vNB for stability at stock speeds.

Quote:

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Originally Posted by afireinside

Well as much as I didn't want to admit it... 1.6v+ for extended periods of time (5 months on water, no idea how many on air when I first got it) has damaged my 940BE. Needs increased vNB for stability at stock speeds.

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vNB? isn't that a motherboard voltage? Even if that's CPU_NB it shouldn't have anything to do with core voltage should it? That's kinda scary...:shocked:

If cpu is scale with voltage then I push it to max 1.55v for 24/7 on air ofc. This is on new am3 cpu's, in era of am2/am2+ cpu smth like 1.6v with good air cooling isnt problem ;] Good = Mugen/Ninja ... push/pull setup and you got some MHz.

Quote:

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Originally Posted by BeepBeep2

vNB? isn't that a motherboard voltage? Even if that's CPU_NB it shouldn't have anything to do with core voltage should it? That's kinda scary...:shocked:

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CPU_NB is what I meant. I guess it's possible I damaged the IMC? Was running that at 1.425 I believe. I remember seeing an official paper from AMD (that I can't find, go figure) and I want to say it said 1.55 was on for CPU_NB, but maybe not. Either way my CPU is NOT happy.

Quote:

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Originally Posted by afireinside

CPU_NB is what I meant. I guess it's possible I damaged the IMC? Was running that at 1.425 I believe. I remember seeing an official paper from AMD (that I can't find, go figure) and I want to say it said 1.55 was on for CPU_NB, but maybe not. Either way my CPU is NOT happy.

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CPU_NB or NBvid or NBIMC ive always kept below 1.55v as per AMD for the IMC DDR2/DDR3.. I see Thurban being slightly lower due to more cores and stress on IMC with higher Freqency Rams.

Just think of the IMC(NB) as another CPU... 1.45volts@3100mhz .

Hence the memory alone coupled with High NB is like having a Supercharger in your CPU .

The Extra Volts up to 1.45v will indeed get things cooking across 6cores and 1800mhz+ ram..

Adding to much Volts or using the Max Volts usually spells Misfire. Voltage is like your Boost.. To much Boost (28psi on the street (and poof there goes the intake/Lower end:D To0 little volts and your NB limited( like a stock supercharger with 6psi).

Keeping a happy Voltage medium on the NB is priceless..Ive maxed lots of CPU's and ive found that 1.4volts or lower is all ive ever needed on C2/C3..

Thurban is an animal , just remeber More NB(IMC) volts will add heat faster than X4cores .Two more cores pushing the IMC(= more Stress).

just my 2cents

If i had a Thurban id VoltPush it to the moon for Ya:D

I've pushed my 965BE to 1.55v on the CPU_NB for bench sessions.

I try to keep under 1.45v for 24/7. Maybe that will be 1.40v now. :shrug:

my Phenom II x3 720BE quad-core runs 3.43GHz @ 1.48V 24/7, most of the time lightly loaded.

Quote:

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Originally Posted by BeepBeep2

I've pushed my 965BE to 1.55v on the CPU_NB for bench sessions.

I try to keep under 1.45v for 24/7. Maybe that will be 1.40v now. :shrug:

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4.1GHz @ 1.40v?
what a nice chip you have

Quote:

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Originally Posted by haylui

4.1GHz @ 1.40v?
what a nice chip you have

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I believe that was his IMC voltage, not cpu vcore

Quote:

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Originally Posted by Mavhenz

This is lovely!

If my Deneb need 1,48 volts @ 4ghz but I read 1,45 volts in Cpu-Z (Voltage drop).

Do I consider the real voltage as 1.48 or 1,45?

1.48?

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CPU-Z reports the voltage that is monitored by the support chipsets such as Winbond or ITE based sensor chips. These are IO chips specifically made to provide montioring, sensing, and feedback (reference) for VRMs, etc.

The quality of the voltage reported by CPUID is directly related to the quality of these chips. They are typically pretty good, in the Asus boards I have looked at in detail, the voltage reported is almost always dead on, to the 3rd sig fig, with a measured voltage from a calibrated Fluke.

Having said that, voltage droop is unavoidable (though some MB makers try load line calibrations to correct for it, none are perfect), VRMs under load will provide less voltage (lesser than the requested) than at idle. It is much like a pressure regulator in which you allow air to flow constantly, the measured pressure past the regulator is always less than the set pressure without air flowing.

Thus it is correct to assume the voltage on the CPU is the reported voltage as a drooped VRM is actuall providing that voltage, not the requested.

Jack

I should have read this thread sooner. I just killed a X2 240. Hell of a chip, did 4.0Ghz without any additional voltage, 4.1 needed some extra volts. While trying to get it stable at 4.2 I set the voltage to 1.6v in BIOS (Board overvolts about 0.025v under load). I ran IntelBurnTest for some time, then I smelled burned electronics and the chip was dead.

2nd Chip is now stable at 4.0Ghz 1.475v. I'm gonna leave it at that.

Quote:

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Originally Posted by digitalfrost

I should have read this thread sooner. I just killed a X2 240. Hell of a chip, did 4.0Ghz without any additional voltage, 4.1 needed some extra volts. While trying to get it stable at 4.2 I set the voltage to 1.6v in BIOS (Board overvolts about 0.025v under load). I ran IntelBurnTest for some time, then I smelled burned electronics and the chip was dead.

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Are you sure it not the board that bit the bullet though? It seems - it's rather easier to kill your board that you cpu nowadays...

People with Thubans & phase changing @ 24/7, should know what I mean :p:

Those voltages are under water right? What about them with a good (high-end) air cooling?

if its just 2 cores it might not be that bad with temps