5 Replies Latest reply on Jan 30, 2016 9:07 PM by t77chevy

    A10 APU throttling for no reason

    leerdnuss

      Hi,

      i recently bought an ASUS A88XM-E, A10 7870k and 2x4GB DDR3 2400MHz  G.Skill Ares RAM.

      When i put load to the APU (Prime95,Games) the CPU begins to throttle after some minutes. I have already checked if it´s a thermal problem, it is not. The temps are all fine and sometimes it throttles at 55C, sometimes at 65C. It also seems not to be a TDP Problem as it does not get above 95W (looked up in Asus AI Suite). I have also underclocked and undervolted it and set every possible BIOS Setting to cause it to consume less power. And also the other way around, i tried giving the CPU a bit more Vcore and Overclocking capability (Power Phase Control, Load Line Calibration,....). it throttles down to 1,6xx GHz no matter what i do, even if i clock it down to 2,5 GHz. This generates massive Framedrops in Games, for example 120-35 FPS in CS:GO.

       

      I have read about some other people who seem to have similar problems.

       

      I hope someone can help and sorry for my english

        • Re: A10 APU throttling for no reason
          techguy

          Is your mobo Rev. A1 and are you using BIOS 1204 or newer? That's what the Asus website shows is required for the A10-7870K

           

          The only times that I have seen a CPU/APU down clock under full load is when the CPU/APU was running too hot or the mobo VRM was running too hot. Some mobos have "light duty" VRM designs that may not be able to handle all CPUs/APUs running under P95 or similar stress tests without the VRM overheating. Gigabyte had a series of AM3+ socket AMD mobos that suffered this problem. After a short period of time the VRM circuit overheats and then it throttles the processor vcore voltage which automatically lowers the processor speed until the VRM cools down then it shifts upwards again for a short time and then back down, continuously.

           

          I looked at your mobo model on the Asus website and it doesn't show any VRM heatsink so this might be the issue? You should also check the 12v voltage line from the PSU when they system is under maximum load to make sure the PSU isn't having an issue with the load.

            • Re: A10 APU throttling for no reason
              leerdnuss

              There is a Scythe Shuriken Big on it which is also cooling the VRMs. All i can say is, that it seems not to be temperature related. And like i said it is also throttling when playing CSS or CSGO. Even underclocked and undervolted. The PSU should not be a problem, it is an thermaltake Berlin 630W with 45 Amps on the 12V Rail. It ran an 95W i7 and dedicated Graphics before.

                • Re: A10 APU throttling for no reason
                  leerdnuss

                  I noticed that running prime95, the CPU does not really care about fan speed. no matter if its on its lowest or highest setting, it will stay around 55-57C.

                  BUT the CPU throttles down much more often on the lower fan speed than on the max. fan speed. So it could be the VRMs or is there something else impacted by this?

                  I guess some of the VRMs are defective or something like that, because at least on stock cpu settings, they have to work at light gaming.

                    • Re: A10 APU throttling for no reason
                      techguy

                      The VRM components are not necessarily defective. They may just be marginal for 100% stress testing with your APU model? They have a built-in circuit that lowers the output voltage when these components reach a certain temp to protect them from burning up. If you can take a small fan and place it so it blows directly on the VRM components next to the APU socket and see if it takes longer before the APU frequency drops down or not. If in fact it takes longer with a fan blowing cooler air on the VRM components I'd contact Asus to see what their take is on this issue. You might be able to install a heatsink on the VRM components but normally this should not be a requirement for a std. mobo listed as supporting your specific APU model.

                • Re: A10 APU throttling for no reason
                  t77chevy

                  the ASUS A88XM-E has no cooler on its vrm and is why its downclocking as its vrms are overheating