binder87 wrote: First thank you for the detailed answer. Though, while it may explain the lack of lower temps, it still doesn't explain why the temp is actually higher despite less power consumption , and why it generally behaves in an erratic way, unlike smt enabled. That's pretty counterintuitive and therefore I'm curious as to why it happens, and also whether it's an isolated case that I have or its an issue with ryzen. If I had another separate ryzen it would be easier for me to check it myself, but I don't. |
Okay, well I can see how it might seem counter-intuitive but nothing a quick refresher on how Electronics work can't fix.
A good way to conceptualise Electricity is to imagine that it's Water... we can literally say that Voltage is Flow Rate, while Ampere is the Maximum Pipe Volume.
As the Flow Rate increases, so too does the Total Volume of Water., increasing the Pressure of the System.
Now there are two ways to alleviate pressure... either we reduce the Flow Rate *or* we increase the Length of the System., as the larger the System we have the more Total Volume of Water is required to achieve an Ideal Pressure.
Even if we're beneath said Ideal Pressure though, the Total Volume of Water in the System still Increases by the amount of Piping that we've added.
If we were to say have a totally closed system going above the Ideal Pressure is actually a bad idea, because what you'll be doing is creating undue stress on the Pipes until they eventually just burst., and as you can imagine that isn't exactly useful for Electronics. As such they use a more "Open" Approach, where Excess Pressure is bled off in the form of Heat., in fact they're designed explicitly to have a much higher operational Pressure Threshold because of this; plus it cuts down on the need for additional materials in construction reducing costs.... blah, blah, blah.
The point here is that because AMD SMT works by enabling a Larger System rather than trying to Maximise the Existing System to operate at it's near Maximum Pressure Constantly., this means that while the Voltage remains the same as does the Amps; the Total Volume (TDP) increases inline with the additional Pipelines that have been Added... it also means that Overall System Pressure DECREASES by the same Margin.
In other words you're trading more Power Efficiency for Performance., the Lower Temperature is merely a side effect of their Lower Efficiency of Performance / Watt.
Hopefully that explains it a bit better.
binder87 wrote: Regarding smt and free performance, while generally true, unfortunately , whether due to windows 10 scheduler issue with thread hopping when the workload is lightly threaded (which amd claimes functions properly, but it doesn't...) or lack of optimization by developers ,or a combination of both, currently most games shows an improvement with smt disabled, and since I mostly game, I don't see a reason to leave it enabled for now. But what's holding me off is this weird temperature behaviour when you disable smt and I was hoping someone would shed some light on it. |
I would like to see some proof of Performance Degradation with SMT today., as from Internal Tests it hasn't been an issue since April / May 2017.
Now as to what exactly was causing this, well neither Microsoft or AMD would actually admit that there was even an issue., instead it was simply resolved shortly after the Ryzen 5 Launch.
As far as I could tell it was never an issue with the Windows 10 Scheduler, but rather Power Management / Optimisation.
If you're still experiencing said issues, I'd make sure you have the latest Motherboard BIOS and Chipset Driver... especially setting Power Management to Ryzen(tm) Balanced or Windows Performance, will generally resolve it.
Still Motherboard BIOS updates to support SMT / Auto Mode., does help as it'll automatically decide when to disable it to maintain performance.
