X370 TaiChi DownCore not working

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   I can appreciate that most, if not all people who buy AMD Ryzen aren't going to look at turning off cores, but the feature is there and I wanted to utilise it to see what impact it has on power consumption reduction.
UEFI/BIOS 3.10

Advanced > AMD CBS > Zen Common Options > Downcore Control

I tried setting this to 4+0 but the system wouldn't boot to Windows.  The black Windows load screen shows with the little white dots circling around, but they just stop.  The system hangs, frozen in this state of non-OS.  I hit the reset button on the case, same thing happens but Windows displays the something or other "Repair...." text under the spinning circle of dots, then a hang.

I have to restart and spam the DEL and F2 keys like a man possessed, just to get back to UEFI (yeah fast boot), and then I can change it back to Auto cores.  F10 (save & exit) and it hangs again.  I have to hold the case power button in for a few seconds to force a power down.  Only then does the system boot fine.

I have tried a hard power down with the other downcore option(s) but that didn't work.

How can I use the downcore options?  It it buggy?

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VUMeter Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 14 Sep 2017 Location: UK Status: Offline Points: 148	Post Options Post Reply Quote VUMeter Report Post Thanks(0) Quote Reply Topic: X370 TaiChi DownCore not working Posted: 12 Feb 2018 at 12:38am
	I can appreciate that most, if not all people who buy AMD Ryzen aren't going to look at turning off cores, but the feature is there and I wanted to utilise it to see what impact it has on power consumption reduction. UEFI/BIOS 3.10 Advanced > AMD CBS > Zen Common Options > Downcore Control I tried setting this to 4+0 but the system wouldn't boot to Windows. The black Windows load screen shows with the little white dots circling around, but they just stop. The system hangs, frozen in this state of non-OS. I hit the reset button on the case, same thing happens but Windows displays the something or other "Repair...." text under the spinning circle of dots, then a hang. I have to restart and spam the DEL and F2 keys like a man possessed, just to get back to UEFI (yeah fast boot), and then I can change it back to Auto cores. F10 (save & exit) and it hangs again. I have to hold the case power button in for a few seconds to force a power down. Only then does the system boot fine. I have tried a hard power down with the other downcore option(s) but that didn't work. How can I use the downcore options? It it buggy?
	X370 TaiChi \| 1700X P3.10 stock clocks \| (2x 16GB) 32GB FlareX 2400MHz.

MisterJ Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 19 Apr 2017 Status: Offline Points: 1097	Post Options Post Reply Quote MisterJ Report Post Thanks(0) Quote Reply Posted: 12 Feb 2018 at 12:59am
	VUMeter, I would suggest you open a ticket with AMD Technical Support. Before you try anymore experimenters, please TURN OFF fast boot. Enjoy, John.
	Fat1 X399 Pro Gaming, TR 1950X, RAID0 3xSamsung SSD 960 EVO, G.SKILL FlareX F4-3200C14Q-32GFX, Win 10 x64 Pro, Enermx Platimax 850, Enermx Liqtech TR4 CPU Cooler, Radeon RX580, BIOS 2.00, 2xHDDs WD

VUMeter Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 14 Sep 2017 Location: UK Status: Offline Points: 148	Post Options Post Reply Quote VUMeter Report Post Thanks(0) Quote Reply Posted: 12 Feb 2018 at 1:09am
	Aye, I will do. Thanks. The good news is that nothing is 'broken' from my limited tests. Currently set back to normal default Auto (all cores) and it boots from cold, reboots and all just fine. I'll contact support and see where that goes.
	X370 TaiChi \| 1700X P3.10 stock clocks \| (2x 16GB) 32GB FlareX 2400MHz.

MisterJ Members Profile Send Private Message Find Members Posts Add to Buddy List Senior Member Joined: 19 Apr 2017 Status: Offline Points: 1097	Post Options Post Reply Quote MisterJ Report Post Thanks(0) Quote Reply Posted: 12 Feb 2018 at 1:23am
	Thanks, VUMeter. Please let us know what you learn. I will post if I think of anything. Enjoy, John.
	Fat1 X399 Pro Gaming, TR 1950X, RAID0 3xSamsung SSD 960 EVO, G.SKILL FlareX F4-3200C14Q-32GFX, Win 10 x64 Pro, Enermx Platimax 850, Enermx Liqtech TR4 CPU Cooler, Radeon RX580, BIOS 2.00, 2xHDDs WD

VUMeter Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 14 Sep 2017 Location: UK Status: Offline Points: 148	Post Options Post Reply Quote VUMeter Report Post Thanks(0) Quote Reply Posted: 15 Feb 2018 at 7:59pm
	Still waiting on a reply from tech support, but I thought I'd add an update here. I turned off ultra-fast boot (seems to not make any difference to boot speed ~26s to Windows desktop), and set Downcore Control to 3+3, essentially turning my Ryzen 7 1700X into something similar to a Ryzen 5 1600X. This worked fine, Windows launched and showed 12 threads in the performance tab of task manager. 4+0 still didn't work though, and I didn't want to jinx my good fortune, so set back to auto until I hear from tech support.
	X370 TaiChi \| 1700X P3.10 stock clocks \| (2x 16GB) 32GB FlareX 2400MHz.

VUMeter Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 14 Sep 2017 Location: UK Status: Offline Points: 148	Post Options Post Reply Quote VUMeter Report Post Thanks(0) Quote Reply Posted: 19 Feb 2018 at 10:06pm
	Tech support got back to me in a timely manor. They had no trouble using BIOS P4.40, and posted multiple screen shots showing Downcore control working bother changed via BIOS and Ryzen Master s/w. However I am hesitant to jump to that version as the rest of my system is stable on P3.10 and I read many issues for lots of folks. This is certainly not a big enough issue to really go any further with. I doubt that much electrical energy would be saved by dropping a CCX, as it's already rather efficient when idle anyway. Seems to be a potential source for problems as it's running outside of the normal and standard way of things. One thing I did do some time ago was to clone the Ryzen Balanced power profile and adjust a number of settings using the Rightmark Power Management utility, which allows for deeper editing that what Windows allows by itself. I've gone more aggressive in terms of core parking and less core utilisation, so for the most part only 2 threads are being used by the system when idle, or 4 threads when browsing. It didn't seem to have much of a detrimental effect on 1080 gaming nor some standard tests like Blender or Cinebench. However I save about 1-2 watts on idle. Maybe that is in the realms of error difference.
	X370 TaiChi \| 1700X P3.10 stock clocks \| (2x 16GB) 32GB FlareX 2400MHz.

JohnM Members Profile Send Private Message Find Members Posts Add to Buddy List Groupie Joined: 20 Feb 2018 Location: UK Status: Offline Points: 267	Post Options Post Reply Quote JohnM Report Post Thanks(0) Quote Reply Posted: 22 Feb 2018 at 7:12pm
	It took me a while to work out what 4+0 and 3+3 mean but I think I understand that it refers to the number of active cores in each CCX. You've shown that 3+3 works and I should think that 2+2 would as well. Those two configurations, along with 4+4, represent real Ryzen products. The thing is, until recently there were no 4+0 products. Now there are the 2200G and 2400G, which only have one CCX but they are not supported by your BIOS so to my mind it seems reasonable that to achieve the 4+0 configuration that you want you will need to update your BIOS. What I'd be interested to know is if you are able to shut down all four cores in one CCX do you also lose half of your L3 cache?
	ASRock Fatal1ty AB350 ITX P4.90, AMD Ryzen 5 2400G, 2x8GB Corsair CMK16GX4M2A2666C16, 250GB Samsung 960EVO, 500GB Samsung 850EVO, 4TB WD Blue, Windows 10 Pro 64, Corsair SF450, Cooler Master Elite 110

VUMeter Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 14 Sep 2017 Location: UK Status: Offline Points: 148	Post Options Post Reply Quote VUMeter Report Post Thanks(0) Quote Reply Posted: 22 Feb 2018 at 7:49pm
	http://www.geeks3d.com/20170503/amd-ryzen-downcore-control/ That shows a 16MB L3 being reported, but that's Winows showing it rather than something more useful. It's an MSI board they are using and this was back in 05/2017. Tech support did provide screen shots with CPU-Z: 4+0 // 4x L1 and L2 // L3 8 MBytes 2+2 // 2x L1 and L2 // L3 2x 8 Mbytes. So, it looks like disabling a CCX disables half the L3 cache too. I would also guess 2+2 would work, but haven't tried. Each motherboard maker does things differently, and although the MSI board looks to have worked with 4+0 almost a year ago, I wouldn't be surprised to find that I would need to update BIOS to take advantage here. Though, I am holding off because of the numerous issues folks are having and the fact that everything else seems to work fine with my system. Why potentially brake it to try and enable something I probably won't find does that much?
	X370 TaiChi \| 1700X P3.10 stock clocks \| (2x 16GB) 32GB FlareX 2400MHz.

VUMeter Members Profile Send Private Message Find Members Posts Add to Buddy List Newbie Joined: 14 Sep 2017 Location: UK Status: Offline Points: 148	Post Options Post Reply Quote VUMeter Report Post Thanks(0) Quote Reply Posted: 29 May 2018 at 2:39am
	Apologies to those not too fussed about this, I am reviving as I have just tested this and it has worked. I used Ryzen Master to disable 4 cores, and now I am running 4-cores / 8-threads. It's saving about 2-3 watts at best, so it goes to show how efficient the Ryzen 7 CPU is compared to a Ryzen 5 and Ryzen 3. I have to admit that I took the Ryzen balanced Power Profile for Windows 10 and edited it to have aggressive core parking, so I could be increasing idle power saving beyond what would normally be seen. Anyway, it works. I had a PSU failure, so I had cleared CMOS and removed the CR2032 battery in my testing of the issue. This may have contributed to a smooth and easy Downcore. I didn't do it through BIOS/UEFI, only via Ryzen Master. Bottom line: Unless one needs it to test, there isn't much point in downcore control. Just adjust your powerplan settings with the Rightmark editor.
	X370 TaiChi \| 1700X P3.10 stock clocks \| (2x 16GB) 32GB FlareX 2400MHz.