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max 24/7 voltage for i7?

R

Rifter

Lifer
Simple question guys, whats the max safe voltage for a i7 930?

Im asking because when i tested my overclock(4.2Ghz) it was summer and i had very high ambients and my CPU would hit 90-93c after a day at full load. Now that its winter it usually stays in the 77-80c range after 24 hours loaded so i have more room to the thermal limit now. I was thinking of finding the max overclock for my CPU, then going back to my current settings for the summer and having a summer and winter OC profile so to speak. I realize my current bus speed of 200 is probably very close to the limits of the mobo but want to push it anyways.

Current voltage is 1.35v in BIOS with LLC enabled as well as xtream phase full power mode, whatever the hell that is. All i know is the voltage reported in CPUZ is 1.336v rock steady under load changes.

Thanks in advance for any answers.
 
1.375 without LLC, and you are 100% safe.

You should still be fine with 1.35 and LLC enabled, but you might be overshooting 1.375 when coming off load. It all depends how good your VRM is and how much you are overclocking (how many amps your VRM is dealing with).
 
Yes, at higher voltages it becomes more dangerous because it can overshoot the maximum safe voltage.

At lower voltages, it does not have any adverse effects, except that finding stability is actually harder because you can't see the brief under and overshoots, so the voltage appears stable to you, but it's not really.

And stability testing doesn't do much to highlight this problem because it's a sequential load, while real life scenarios load is constantly changing, so you might crash from an undershoot.

LLC is pretty much a gimmick.
 
good to know, thank you!

Do you know anything about the asus xtream phase full power mode bios option? should this be enabled or disabled?
 
Yes it should be enabled.

It will disable the Asus EPU and make the VRM work harder to provide cleaner energy, but they will be less efficient.

On for OC, Off for Efficiency.
 
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How are these "facts" known?

I am an active EE & have OC-ed for years. I read a lot of what OC advisers say, but I would really have to struggle to answer with such confidence.
 
I'm a supporter of LLC; however, it does depend on the persons situation. Unfortunately you cannot just make blanket statements saying LLC is good or LLC is bad as we don't completely know how it affects the processor.

If LLC when overclocking even moderately retains its specifications, I wouldn't worry about it when using tame voltages such as 1.4v. It really only becomes a theoretical problem when pushing voltages above 1.45-1.5.

Idontcare said:
Yeah the poor man's method here would be to think of the "area under the curve". Voltage over time. What's worse, 1.7V for 100ms or 1.6V for 500ms?

Neither option is good, but knowing which is worse is only half the question, the other half of the question is figuring out when not good means unacceptably not good versus acceptably not good.

For example, running my chip at 1.6V is not good, but that may merely mean the chip will die in 3 yrs instead of 20. So that is acceptably not good. But running my chip at 1.7V may mean it dies in 6 months, and for me that may be unacceptable...ergo unacceptably not good.

So is LLC "not good"? Undoubtedly. Is it unacceptably not good? No one has reported LLC killed their chip yet, and we got a pretty sizable active Internet community these days.

Is LLC more acceptable than running your chip at an otherwise higher idle voltage to compensate for the lower Vcc during load because of Vdroop? Contrary to Anandtech's article on the topic, it would appear that it is more acceptable in certain scenarios, as soccerballtux outlined.

I'll add my personal experience to this otherwise theory-based discussion. Without LLC my QX6700 required 1.60V for 4GHz stable at load (this was under phase, so scale the GHz down but keep the Vcc the same to convert this to an "on air" example) but with LLC my chip only needed a 1.50V Vcc. (edit: corrected the voltages, I had them 0.05V too high once I looked at my notes, memory getting weak)

Now the dominant mechanisms of voltage induced degradation are exponentially dependent on the voltage (i.e. your typical activation barrier kinetically limited reactions), so the ability to run my chip 0.1V lower in Vcc during all those hours of the system being idle means a substantial improvement in lifetime versus the trade-off that comes in transients that may spike to 1.75V (0.2V over-volt transient) for a few hundred microseconds when the chip goes from loaded to unloaded.

Both options are *not good* for my chip by Intel's specs and standards, but the question is whether or not one of the two options is unacceptably not good. I have no way of knowing, but I opted for the LLC choice and ran my chip at 0.1V less. It may have merely made the difference between my chip living 4 yrs instead of 5 yrs, I have no plans of giving it the chance to let me find out. It will be replaced long before then.
Click to expand...
 
Ben90 said:
I'm a supporter of LLC; however, it does depend on the persons situation. Unfortunately you cannot just make blanket statements saying LLC is good or LLC is bad as we don't completely know how it affects the processor.

If LLC when overclocking even moderately retains its specifications, I wouldn't worry about it when using tame voltages such as 1.4v. It really only becomes a theoretical problem when pushing voltages above 1.45-1.5.
Click to expand...


Maybe you don't know how it affects it, but some of us do.

vdroop was designed so that the voltage delivered to the processor is never above what is manually set in the BIOS (or in the VID table of the processor).

If you decide to remove vdroop, then whatever undershoots and overshoots you get when going into and coming off load are yours to deal with. Depending on how much stress your VRM can handle, if the undershoot is low enough you get an nice BSOD. If the overshoot is high enough, you damage and affect the processor's long term reliability.

Obviously it was designed as a way to deal with cheap power delivery circuitry used on entry level and OEM boards. Expensive power delivery circuitry found on high end motherboards are designed to easily handle far beyond stock power draw, and all the amperage that comes with overclocking, so running without vdroop surely is safer than with cheap power delivery. But it still against design, so use at your own risk.
 
LLC can definitely help in heat bound situations.

Load line droop was designed as a way to deal with cheap power delivery circuitry used on entry level and OEM boards well before LLC was around.
 
PsiStar said:
How are these "facts" known?
Click to expand...

Actually Intel specifies the most upper boundary for every processor. For example, 1.375V for i7 930. Of course, you still have a little bit of leaway after that, but Intel doesn't consider it safe. You can run i7s at 1.40-1.45V, but it's not recommended on air cooling.

Rifternut, honestly, I wouldn't bother trying to find a higher overclock. If anything, see if you can lower your CPU voltage and keep the same overclock. Overclocking Core i7 from 4.2ghz to say 4.3ghz only brings a 2.4% performance difference that's impossible to discern. However, the power consumption beyond 1.32V and 4.0ghz overclock is simply astonishing.

Chances are your Seagate 7200.12 hard drive is the biggest bottleneck by far and going beyond 4.2ghz is going to bring no performance improve you'll notice (unless we are counting minutes in video encoding work 🙂)
 
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RussianSensation said:
Actually Intel specifies the most upper boundary for every processor. For example, 1.375V for i7 930. Of course, you still have a little bit of leaway after that, but Intel doesn't consider it safe. You can run i7s at 1.40-1.45V, but it's not recommended on air cooling.

Rifternut, honestly, I wouldn't bother trying to find a higher overclock. If anything, see if you can lower your CPU voltage and keep the same overclock. Overclocking Core i7 from 4.2ghz to say 4.3ghz only brings a 2.4% performance difference that's impossible to discern. However, the power consumption beyond 1.32V and 4.0ghz overclock is simply astonishing.

Chances are your Seagate 7200.12 hard drive is the biggest bottleneck by far and going beyond 4.2ghz is going to bring no performance improve you'll notice (unless we are counting minutes in video encoding work 🙂)
Click to expand...

Well i do alot of video encoding, but honestly its more about finding the max OC of the chip than any actual performance gains. Unfortuantly the 1.35v i have set in the bios now is the lowest it will take and still be what i consdier 100% stable, if i lower it to even 1.34v it will get errors in the 4th core in prime95 between 24-48 hours into the test. Some people consider 24hours of prime stable but i prefer to be able to take 72hours no errors before i consider it 100%. Especially since sometime i set up batches of files to be encoded that can take up to 4 days to complete, so loading my system to 100% for longer than 24hours is not unrealistic for my use.

I was planning on getting a SSD as soon as the next gen intels hit which according to all the rumors from 6-12 months ago was supposed to be by now or sooner. But we all know how the waiting game goes. Im going to pick up a SSD at a boxing day sale for sure, new intels on the market or not i dont care anymore intel can stuff it. I'll probably pick up a vertex 2 or a G2 intel 160GB depending on what i can find cheap on boxing day.
 
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