Ryzen 3900X (or 3950X) on X370.

TheSlySyl

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You got 60% at stock, omfg? That means your board is goosing the chip by quite a bit
That was exactly my thinking and would also explain the 50C+ idle temps.

I know my board was never made or expected to have a 3900X and that there was a risk involved. So I'm honestly just shocked at the stability of all this.

I'll disable PBO tonight after it goes idle again. I don't expect the transcoding job to be done for a while.
 

GSDragoon

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Feb 24, 2004
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Yeah, temps can spike up very quickly and fluctuate a lot. It sounds like you have a lot of stuff in the background keeping things warm. Get a true idle system and only monitor the CPU temp. It will probably go down.
 

Azif

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Any tips?
I have the same board gaming K4 and just got a 3800x so assume it should run...
 

sabrewolf732

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nice to see these 3900x's are so toasty. I just got mine set up with a raystorm pro, 420mm radiator, and d5 pump and I also idle in the high 40's to 50s. Prime 95 load goes up to 80c. I remounted block twice.
 

TheSlySyl

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Any tips?
I have the same board gaming K4 and just got a 3800x so assume it should run...
Yeah, update the BIOS, I mentioned the exact revision that I used in a previous post, but the board booted with my 1700 all the way up to 5.50 (AGESA 1.0.0.3)
Once I got the new CPU installed and got to windows I updated the BIOS again.

After some memory tweaking everything was stable.

I then had to massively undervolt my processor to get temps in line, but that could be particular to my motherboard or situation.
 
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sirmonkey1985

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nice to see these 3900x's are so toasty. I just got mine set up with a raystorm pro, 420mm radiator, and d5 pump and I also idle in the high 40's to 50s. Prime 95 load goes up to 80c. I remounted block twice.

just the nature of the beast.. chiplets are too small to transfer heat efficiently to the IHS. that being said make sure you don't have high performance mode set in the windows power settings. should also make sure you have minimum cpu set to 5%. should drop your idle temps so that it drops below 1v at idle.

Yeah, update the BIOS, I mentioned the exact revision that I used in a previous post, but the board booted with my 1700 all the way up to 5.50 (AGESA )1.0.0.3
Once I got the new CPU installed and got to windows I updated the BIOS again.

After some memory tweaking everything was stable.

I then had to massively undervolt my processor to get temps in line, but that could be particular to my motherboard or situation.

just be careful with undervolting because zen 2 isn't like old processors were it'll just instantly black screen due to low voltage. the cpu will still attempt to run and lower clocks internally even though the reported clock speeds look normal so double check your performance with something like CB20 at stock and then undervolted. i think it was der8auer that did a video talking about it.
 

thesmokingman

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nice to see these 3900x's are so toasty. I just got mine set up with a raystorm pro, 420mm radiator, and d5 pump and I also idle in the high 40's to 50s. Prime 95 load goes up to 80c. I remounted block twice.

You are probably looking at the default cpu sensor. P95 will load up to 80c, that's a given its Prime. Now if you are loading Cinebench to 80c then yea you would have a problem. Regarding the cpu sensor, default reading on 99% monitoring apps shows not only cpu temp, but also all 24 individual cpu sensors, and temps for both CCD. That's why you see high temps because the cores are reacting to context switches, basically doing their job in ms.

My 3900x idles at 35c, doesn't spike up at all. That's because I'm not using the default cpu sensor, instead am using die average.
 

sabrewolf732

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You are probably looking at the default cpu sensor. P95 will load up to 80c, that's a given its Prime. Now if you are loading Cinebench to 80c then yea you would have a problem. Regarding the cpu sensor, default reading on 99% monitoring apps shows not only cpu temp, but also all 24 individual cpu sensors, and temps for both CCD. That's why you see high temps because the cores are reacting to context switches, basically doing their job in ms.

My 3900x idles at 35c, doesn't spike up at all. That's because I'm not using the default cpu sensor, instead am using die average.

What are you using for temp monitoring?

sirmonkey1985 seems like my idle voltage is constantly ~1.4-1.5v
 

thesmokingman

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TheSlySyl

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just wondering why not just go for a b550 or an x470?
I already had an X370 board installed and I didn't want to spend the money or time to upgrade it to a B550 or X470. Now that I'm at at over a month with my 3900X on my X370 and before the last windows update, I was sitting at 18 days uptime. I think I made a good decision.
 

orijin

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I already had an X370 board installed and I didn't want to spend the money or time to upgrade it to a B550 or X470. Now that I'm at at over a month with my 3900X on my X370 and before the last windows update, I was sitting at 18 days uptime. I think I made a good decision.

True if money is a factor, might as well leave it as it is if its still working
 

Lakados

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Running a 3900 on my B450 is problematic at worst and given the specs of most 300 series boards I can’t recommend it. Could you make it work, I’m thinking so, given the price you are about to spend on the CPU I’m not sure it’s gonna be worth the headaches you may experience though. I would just find a good budget B550 board they exist, save yourself a lot of headaches.
 

thesmokingman

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I recently threw my ole 3900x into a x370 Carbon Pro. The Carbon Pro is a decent mb to begin with, but anyways it went fine. The board didn't hold the 3900x back. Cinebench R20 scoring is right where it should be. I went back and forth on the board, but at the end of it it made sense to try the board first and see. And yea it went fine. But as I mentioned you want to start with a decent platform to begin with.
 

crazycrave

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I run a 3700x on the MSI x470 Gaming Plus as I flashed it myself .. find cool & quiet and disable it ..
 

motqalden

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This exact scenario was on my "To Do" list and I finally did it. Picked up a used 3900x for about 400 USD and i swapped it in place for the Ryzen 1700 that i was previously running. My motherboard is Asus Prime X370 Pro which is a 6 Phase VRM so it will be fine since I am not overclocking.

I had 16BG of 3200MHZ ram which i never got fully stable past 2933 on this board with the R1700 , but I bought a second kit of the same ram and all 4 sticks booted easily at their XMP / DOCP with the 3900x.
So far so good!
 
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