Ryzen 3900x Undervolt - better than OC?

B1gdeano

B1gdeano

B1gdeano

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Hi,

Not long got hold of my 3900x - coming from Intel historically I am trying to get my head round how it works! Always used to OC my chips but having a play here it doesnt seem to have much point in even messing with OC as results arent much to talk about for the effort.

What I am really keen to do however is drop the voltage as by default, my Mobo wants to drop 1.47v through the CPU and idle temps are around 50c!

Doing some testing using Ryzen Master I can get a stable 4.25 all core at 1.3v, with PBO disabled in the BIOS, which dropped idle temps to about 38c. Though I am sure I am better off leaving PBO on in BIOS as it did boost higher than 4.2.

If I was to just put a manual vcore of 1.3 into the BIOS and leave everything else auto would this work the way I am hoping?

Away from my PC at the moment and just thinking about it so cant test, but ideally want run this by people with more experience with Ryzen 3s

From searching the net it seems that OC is generally a bit pointless and better to focus on the RAM?
 
Keep pbo enabled and use a minus voltage offset keep stepping down from 0.00625 to say 0.01875 and check your core MHz in stress tests like Cinebench20

Other way is a manual volt input say 1.3 or 1.325 but and force an all core overclock but the. Your ccx2 will be not as good silicon as the ccx0 so will hold you back. (You could run different dividers on the ccx’s chipletes)
 
Cheers guys

Going to have a bit more of a play today and see whats what

Im basically after the lower temps, so lower voltage, even if it sacrifices a little bit of peak boost. Cant see it affecting much in the real world outside of benchmarking tbh
 
As an aside - how much of an improvement is faster RAM on these? Does the speed and latency make a discernible difference when using it, outside of some benchmark numbers?
 
B1gdeano said:
As an aside - how much of an improvement is faster RAM on these? Does the speed and latency make a discernible difference when using it, outside of some benchmark numbers?
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for the very best performance cl14 - cl16 ram kits are best, but for more convenience out of the box cl16 would be best, simple plug and play, enable docp and away you go, if you don't mind playing with the bios settings then cl14 kit's will most likely work, as above cl14 may be plug and play but it can vary.

which ever kit you opt for look at 3600mhz if you run a ratio 1:1 with the cpu (1800mhz IF) the gains are pretty good (cl14 or cl16)
 
wookiee87 said:
for the very best performance cl14 - cl16 ram kits are best, but for more convenience out of the box cl16 would be best, simple plug and play, enable docp and away you go, if you don't mind playing with the bios settings then cl14 kit's will most likely work, as above cl14 may be plug and play but it can vary.

which ever kit you opt for look at 3600mhz if you run a ratio 1:1 with the cpu (1800mhz IF) the gains are pretty good (cl14 or cl16)
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Thanks - think I will replace my current 3600mhz pair with some better quality ones then. They arent great specs - 18/22/22/42!

Want some of those 16/16/16/36 ones....
 
B1gdeano said:
Thanks - think I will replace my current 3600mhz pair with some better quality ones then. They arent great specs - 18/22/22/42!

Want some of those 16/16/16/36 ones....
Click to expand...

my current ram is the same timings as yours cl18, i have the new 8pack ripper 3600mhz cl14 (14/15/15/35) kits on order XD
 
I undervolt mine by 0.102 volts and turn pbo off.

Max temps under load are 65c, and idles at mid thirties. It will hit 4.6ghz on 2/3 cores on the first chiplet with the rest of the core at 4.575. The second chilplet will boost to 4.375 to 4.4ghz.
 
Just be careful undervolting that you don't lose performance. You can undervolt by a lot and still hit high clock speeds but performance reduced..
 
Well i got to be honest - I got bored of messing about so decided to just put a very small -offset and all else on default. my idle seems to have dropped to around 1v at idle. I dont actually think my tools were reporting the volts correctly so just sticking with either CPUZ or Ryzen Master. Idle temps about 35c and in games around the 65c mark, which I dont feel is too bad. Im sure I could improve it but in all honesty I just dont feel its worth the time for the results in games, which is what I bought it for.

Having been digging for safe voltages etc, I seem to see AMD saying 1.4-1.5 is ok for low loads? In that case Im not worrying too much as under load the v drops down to about 1.26 so its not like its getting caned.

Im sure I will eventually spend some time messing properly but right now I am just enjoying it! Too many conflicting ideas about whats best, so going to see later when a consensus is made on best practice.
 
no idea what said:
Just be careful undervolting that you don't lose performance. You can undervolt by a lot and still hit high clock speeds but performance reduced..
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How are you measuring performance?

My Cinebench is 7350 at 0.102v undervolt vs 7200 at 0.065.

My all core boost drops from 4.150 all core to 4.095 all core, temps are a lot lower with the higher under volt too.
 
my 3900x, if i put back to stock speed i get around 7100 in cinebench r20 (not sure on clocks), but when i set a all core overclock of 4.4ghz @1.335v my r20 score sky rockets to just shy of 7700 points which is awesome, likely to improve further when i swap out my cl18 ram for the new cl14 on order :)
 
nutsnut said:
How are you measuring performance?

My Cinebench is 7350 at 0.102v undervolt vs 7200 at 0.065.

My all core boost drops from 4.150 all core to 4.095 all core, temps are a lot lower with the higher under volt too.
Click to expand...

Cinebench is definitely a good measure of performance. Undervolting can definitely help, but only to a certain point. It's just sometimes deceiving because it can still boost high when the voltage is too low, but will lose performance.
 
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