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Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by paulmd on Friday February 21, 2020 @12:47PM (#22385062)
Prime95 has been a bad test for years now. Literally since the introduction of AVX2, it has been known that overclocking and running Prime95 will cause rapid electromigration and processor degradation on Haswell-E if you attempt to overclock. It's fine for like a few minutes but you should not attempt to do 24 hour Prime95 runs like people used to do, that was in the days before AVX was a thing.

https://rog.asus.com/articles/usa/rog-overclocking-guide-cor...

It also does not test all parts of the processor equally, it really just is slamming the cache and the AVX units. You can be "Prime95 stable" and still crash in other things. It's just not a good test anymore in multiple respects.

Same thing for Furmark on GPUs. And nowadays GPUs are actually smart enough to realize they're running a power virus and the power management pulls back the power. So again, it doesn't demonstrate anything. Zen2 is supposed to work the same way, if it realizes you're redlining the chip then it should be clocking down somewhat.

Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by jrockway on Friday February 21, 2020 @12:50PM (#22385102)
No sequence of instructions should cause the machine to reboot.
Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by wtallis on Friday February 21, 2020 @01:03PM (#22385215)
That's an excusable outcome if you're overclocking or otherwise tweaking critical operating parameters beyond their safe default ranges.
Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by marmaduke on Friday February 21, 2020 @02:07PM (#22385802)
Except the 'reboot' command? I'm always curious how it works.
Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by monocasa on Friday February 21, 2020 @03:08PM (#22386263)
Normally you'd ask the chipset so that it can reset all the peripherals at the same time.

On Intel you can also intentionally "triple fault" the CPU and that'll cause it to reset. The way that works is you tell the CPU that it doesn't have interrupt handlers anymore, then cause a software interrupt. Then the CPU will first try to call your interrupt handler (but that'll fail because you told it there are no handlers), then errors during an interrupt cause a "double fault" interrupt that's supposed to handle those errors (but once again, there's no handlers), so now you're in a "triple fault" condition and the only way to recover is to reset, so that's what the CPU does.

Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by mrob on Friday February 21, 2020 @02:04PM (#22385769)
"Power virus" is a propaganda term invented by hardware manufacturers as an excuse to avoid fixing their defective hardware.
Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by paulmd on Friday February 21, 2020 @02:21PM (#22385911)
Designing chips that can be safely run at redline 24/7 will inevitably involve a significant reduction in voltage (and thus clocks) for the 99.99999% of users who aren't running them at redline 24/7.

Would you buy a GPU that you could safely run Furmark on 24/7 if it was limited to, half or 3/4 of the clocks? That's basically what you're proposing. I seriously doubt that you would actually lay money down for that shit. The market as a whole certainly wouldn't, they would buy the card that's faster under actual real-world workloads and/or didn't require manual overclocking to achieve its potential in real-world workloads.

The good news is that you can have it both ways. Modern power management is smart enough to figure out when you're running a power virus and it will downclock to those safe levels, while us normies can get competitive clocks when running our real-world code. It works pretty well most of the time.

Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by theevilsharpie on Friday February 21, 2020 @08:09PM (#22388680)
> Would you buy a GPU that you could safely run Furmark on 24/7 if it was limited to, half or 3/4 of the clocks?

Given that modern GPUs have complex frequency scaling algorithms that take temperature and power usage into account when setting clock speed, there's a good chance that a modern GPU will do exactly that.

> Modern power management is smart enough to figure out when you're running a power virus and it will downclock to those safe levels, while us normies can get competitive clocks when running our real-world code.

Which is perfectly fine, as long as the clock speed behavior is disclosed (which it is).

What isn't fine is a product running at such a high speed from the factory that running certain workloads damages it.

Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by Filligree on Saturday February 22, 2020 @09:01AM (#22391048)
If you look back at the OP, he specified "while overclocking".

I believe that's where the issue lays. Overclocking usually also means increasing the voltage.

Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by rasz on Friday February 21, 2020 @03:05PM (#22386233)
>electromigration and processor degradation on Haswell-E

So what you are really saying is Intel made another defective product.

Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by paulmd on Friday February 21, 2020 @03:54PM (#22386615)
No, I'm just using that as an officially documented example of Prime95 being problematic.

AMD is subject to electromigration as well. I've seen a couple guys on Reddit already degrade their Zen2 chips from pushing 1.4V through them just during normal usage, not even Prime95. Literally weeks of usage.

Anti intel circlejerk ahoy.

Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by RobLach on Friday February 21, 2020 @12:59PM (#22385173)
That sounds like it’s a great test actually.
Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by paulmd on Friday February 21, 2020 @01:16PM (#22385343)
What part of damaging your processor due to current draw, while not actually demonstrating any particular level of processor stability, sounds like a great test?

Nice contrarianism.

Yes, you can run it, and it should run successfully. Yes, sustained testing will rapidly damage your processor and cause notable performance degradation (reduced maximum overclocks/increase in required voltages) within a matter of days, and yes, you can still crash in Aida64 or other stress tests because it's not testing the whole processor very well.

It's far outside the normal current draw, even compared to other AVX2 loads like video encoding. It's an AVX load that fits entirely inside instruction cache and will hammer the AVX2 units nonstop at the maximum possible rate with absolutely no other instructions going to any of the other units. That's not how any other workload behaves, even video encoding. CPUs are not designed around that, they're designed for some reasonably normal mix of instructions.

Yes, it's a good idea to stress your processor a bit more than normal to prove it's stable, but if you make your 'proof charge' too large you will still damage the firearm.

Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by abstractbarista on Friday February 21, 2020 @01:30PM (#22385461)
I don't understand, when I buy a processor I expect it to work 100% load for all of the instruction set. Anything less is a defective product, and should be returned.

Furthermore, it should be able to do this 24/7 for years at a time.

This test, assuming it actually does kill the processor or stops executing, clearly indicates it should be returned.

Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by paulmd on Friday February 21, 2020 @01:33PM (#22385496)
It's fine at normal clocks. Not good for the chip, but it won't kill it within the normal operating lifetime (say, 3-5 years). That's why chips ship with a little more voltage than they need, so that they can suffer some electromigration and still function.

Overclocking? Yeah, it'll kill it quick, and that's your problem, because you're operating it outside normal specifications (more voltage than designed). If that's your standard, that you should be able to overclock and then redline the chip 24/7 for an unlimited period of time and it should never kill the chip, then you're going to be disappointed.

The fact that Threadripper is having problems is definitely a fault but it's something that you really shouldn't be doing anyway (and it sounds like the problem is the motherboard not the processor).

More generally: this is like arguing that you should be able to buy a camry and run redlined 24/7 and get the inevitable engine failures covered by warranty. If the manufacturer finds out you're doing that, they're not going to cover it, because it's not normal usage. Somehow people think it's a reasonable expectation for processors.

Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by jotm on Friday February 21, 2020 @02:20PM (#22385893)
I agree Prime95 is overkill, but a processor should be able to handle it.

This is like the cooling argument all over again - "your cooling system is good enough for normal workloads". No, it must be good enough for permanent full load! Like a CPU under Prime95. If your heatsink lets it overheat, it's defective. You saved a few pennies on the copper and now it's a defective product.

Same for Prime95, the CPU must be able to run it for days at end and last ~5 years. Doesn't seem like too much to ask for, imo. Intel says their chips will run at 98 degrees for years, so why would a full load like Prime95 kill them in days?

One other thing, overclocking these days is actually undervolting combined with raising clocks. The old school "just raise the voltage" is a bad way to do it on any Intel chips post-Sandy Bridge...

Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by vbezhenar on Friday February 21, 2020 @03:29PM (#22386396)
If you overclock CPU, you lose warranty. Even if it's K-series which is made for overclocking. And stock settings probably are safe.
Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by jotm on Saturday February 22, 2020 @05:01AM (#22390212)
Yeah I did mean at stock settings.

If you overclock, you're responsible. Losing warranty sounds acceptable to me. Better than manufacturers doing everything to make overclocking impossible.

To me, it's a great way to get more performance out of an old chip, the warranty would be expired at that point.

It is hard to prove a CPU was overclocked though, so I can see some people taking advantage of that.

Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by illumin8 on Friday February 21, 2020 @11:12PM (#22389378)
Did you notice that in the original article he is running the stock clock speed? If a CPU can't handle any instructions it supports at stock clock and voltage for any period of time it is defective, full stop.
Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by jdietrich on Friday February 21, 2020 @03:51PM (#22386589)
Change the word "processor" for "car" and the absurdity of your argument should be fairly obvious. Most ordinary cars will provide reliable transport for many years, but will literally catch fire after a few hot laps on a racetrack. It makes no sense to design a passenger car with brakes, suspension, cooling and tyres that are massively over-engineered for normal use just in case the owner wants to go endurance racing.
Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by betaby on Friday February 21, 2020 @05:34PM (#22387636)
3970x is a race car in your analogy, and thus should not catch fire
Re:AMD Threadripper 3970X under heavy AVX2 load: Defective b... by BubRoss on Friday February 21, 2020 @03:36PM (#22386455)
Damaging the processor? A CPU being unstable while overclocked doesn't mean it is damaging the CPU.