question about undervolting

Hello,

I am trying to undervolt my 4980 but at some point it has a tendency to crash when I am surfing on the internet.
I am not really sure to understand why because it stable in game and under benchmark.
I tried:
-50mv on core,cache and graphic.
-I suspected the graphic undervolt to be the problem so I tried -60mv on core and -40mv on cache

But still at some point it crash during surfing session.

I tried normal and high performance, it does not help.

Why it does it crash when the load on the CPU is low? Once again I was playing the witcher 3 and MSG5 for hours with no laptop rebooting.

Another noob question:
If the power consumption is constant (47W) and if you reduce the voltage, then it means that more current is injected on the CPU, no?
So why does it run cooler?

thank you

 

I don't know about the crashes however I don't think power consumtion is constant.

 

Let's address the points one by one...

That's the thing about undervolting - there are different limitations to it. For example, mine runs at -115mV stable for ages on benchmarks, but crashes the moment I'm in-game. The only way to figure it out is by extensive testing for your specific use cases, and figuring out an acceptable point of stability for you.

-50mV is just an average guideline (most laptops I have are happy to go beyond that, some refuse to go beneath -30mV). High performance is preferred for figuring out your maximum undervolt, since it removes low CPU frequencies (and thus voltages) as being another cause of instability.

So as mentioned above, there's more than just one limitation which prevents a successful undervolt.

This is an interesting one. I brought this up with my friend who does electrical engineering and he asked the exact same thing. Well, it's just different AFAIK - not specialized in details of it. But it does run cooler since voltage increases heat exponentially as you scale it up, it makes sense that it decreases exponentially as you scale it down (until point of diminishing returns of course, which is not far from the standard voltage set for the CPUs).

 

Thank you

 

I've been playing around with undervolting my i7-4710 and have found the same thing, an undervolt is stable at high clocks but I get a blue screen on idle clocks, if I just leave the system sitting there for some time.

If you find a nice stable undervolt for high clocks, you can create a profile in XTU for a game or program and apply it with the app pairing feature. The undervolt will only apply when the game or program is in the foreground, if you alt+tab back to the desktop or explorer, your default settings will apply. So that gets past the issue of BLUE screens at lower clocks because games don't really let the CPU idle.. This won't help you extend battery life, but it will help with temps. I am undervolting for temperature reasons, so this works for me.

The same goes for a program that is CPU intensive that maybe doesn't use the GPU, you can set up a profile to apply a full overclock at stock clocks, when you are running that program and not worried about heat.

By experimenting I have found that my chip blue screens at idle when I undervolt the cache voltage even by -15mV.
I can get a -90mV underclock on the CPU voltage only, and can over clock all 4 cores to x35 with that and it is stable in Prime95 and at idle. If I want to overclock the single and double core frequencies to the max multipliers of x37 and x36 I have to use stock voltage for it to be stable.

So just play around with it and take it in steps!

 

Thank a lot

I'll try to undervolt only the core CPU voltage then.

 

power consumption aint constant, once i downvolt my cpu its peak power consumption under load also slowly declines, same with idle wattage but on a smaller scale...

and its true that ull have to check each undervolt setting on its own to isolate any instabilities. best scenarios would be high load (prime95/intel xtu/occt, etc), medium everyday load (browsing/gaming/etc) and idle (leave the machine switched on overnight).
only once uve covered all these areas u can consider your undervolt setting stable

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