Question Several Questions on my 3950X

marcUK2

Member
Sep 23, 2019
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Hi, running a 3950x on an admittedly inexpensive MB (Asus Prime B450M-A), with 48GB Ram, 2060S, and 650W Corsair CX650M PSU.

1. At stock I get a all core boost of 3.9GHZ under CB20 (long term) - Is this a bit bad for a DR4Pro - Would you suggest a reinstall?

2. Using a darkrock 4 pro, I can only get All Core Overclock stability at 4200 Mhz, using 1.35V (with some thermal throttling). (I also get 4100 @ 1.275V and 4000 @ 1.2V with no throttling) Looks like my specimen is not a great example.?

3. I disabled PBO in my motherboard, but apparently this does nothing, as RyzenMaster, CPUZ, and CPUID HWmonitor, still show the chip boosting to 4.65GHZ and using 1.48V, which I dont like. Is this really OK for long term durability (this PC may be 3d rendering for days at a time)

4. Is it a common feature in a MB to limit the vMax to say 1.35V if PBO is enabled - thus limiting PBO boost clock, but allowing for a bit of a boost (I'd be OK with a boost of 4.4, I dont care about the few microseconds of 4.7 if its eating voltage to get it)

5. Under high Overclocking, I hear a slight random clicking noise. At first I thought a cable was clipping a fan blade, but extensive checking and manual fan override testing reveals no such interference. What else could be causing the (faint) clicking. It doesnt appear under stock conditions. Something on the MB, or PSU? Its very hard to determine where it comes from. For now I am keeping to stock speeds.

Thanks
 

JoeRambo

Senior member
Jun 13, 2013
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Hi, running a 3950x on an admittedly inexpensive MB (Asus Prime B450M-A), with 48GB Ram, 2060S, and 650W Corsair CX650M PSU.
That is not a great situation to be in. I am not familiar with that exact MB, but 3950X pulls high wattage loads, VRM temperature is key, it might start throttling or blow up under sustained load. Would need to read review and check if there is VRM temp sensor in HWINfo64, might need to install better heatsinks.

I'd look for better MB with better VRM and cooling in $150-225 range there are plenty.


1. At stock I get a all core boost of 3.9GHZ under CB20 (long term) - Is this a bit bad for a DR4Pro - Would you suggest a reinstall?
It sounds okayish for stock, as long as score is a bit north of 9000, it is fine. The decision to reseat the cooler should be driven by temps


2. Using a darkrock 4 pro, I can only get All Core Overclock stability at 4200 Mhz, using 1.35V (with some thermal throttling). (I also get 4100 @ 1.275V and 4000 @ 1.2V with no throttling) Looks like my specimen is not a great example.?
1.35V is not recommended at all, esp not on weak MB. And I feel overall the strategy of manual voltage/OC is not wise for these CPUs. As you see, you gain like 100mhz sustained with manual voltage? Might as well leave at stock and apply undervolt of 0.05V or 0.1V and see what happens?

3. I disabled PBO in my motherboard, but apparently this does nothing, as RyzenMaster, CPUZ, and CPUID HWmonitor, still show the chip boosting to 4.65GHZ and using 1.48V, which I dont like. Is this really OK for long term durability (this PC may be 3d rendering for days at a time)
Those are irrelevant voltages, CPU selects up to 1.5V in those light load situations and AMD designed it that way. What really matters is what voltage/amperage/temps/clocks are under Your load.

4. Is it a common feature in a MB to limit the vMax to say 1.35V if PBO is enabled - thus limiting PBO boost clock, but allowing for a bit of a boost (I'd be OK with a boost of 4.4, I dont care about the few microseconds of 4.7 if its eating voltage to get it)
That is overcomplicating things, i have personally found best results with either carefully tested undervolt, or just setting PBO 300/230/230 and focusing on memory tuning, cause that's where real performance was found in my testing.
But do note, that i don't recommend either on Your MB, 3950X pulls insane amperage once out of stock.
 

DrMrLordX

Lifer
Apr 27, 2000
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@JoeRambo

He should probably be undervolting. Though that may not save his VRMs if the chip continues to hit the normal socket power limit anyway by pushing higher clocks/more amps.
 

marcUK2

Member
Sep 23, 2019
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32
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@JoeRambo

He should probably be undervolting. Though that may not save his VRMs if the chip continues to hit the normal socket power limit anyway by pushing higher clocks/more amps.
i tried a minus 0.1v offset in the bios, but CB crashed. Now I am running at stock, with the MB defaults with the correct XMP and everything is stable, I think I will leave it as this for a while and monitor stability
 

Chicken76

Senior member
Jun 10, 2013
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@marcUK2 That board has NO HEATSINKS ON THE VRMs!!! I don't know the performance of those VRMs but the board being inexpensive tells me that they are not some super-duper components capable of running cool at that load, so it will start to smell soon.

1585658263497.png

That CPU-Motherboard combination is not a good one. My recommendation is to buy a better board that can handle that CPU at full load.
 

marcUK2

Member
Sep 23, 2019
40
32
51
@marcUK2 That board has NO HEATSINKS ON THE VRMs!!! I don't know the performance of those VRMs but the board being inexpensive tells me that they are not some super-duper components capable of running cool at that load, so it will start to smell soon.

View attachment 18923

That CPU-Motherboard combination is not a good one. My recommendation is to buy a better board that can handle that CPU at full load.
Youre right of course, For now I will stick to stock operation, and be happy. Afterall this is still HEDT performance that would cost 4x a year ago. Maybe I will upgrade if I get instability, but at stock, its actually running totally OK.
 
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lightmanek

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Feb 19, 2017
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Youre right of course, For now I will stick to stock operation, and be happy. Afterall this is still HEDT performance that would cost 4x a year ago. Maybe I will upgrade if I get instability, but at stock, its actually running totally OK.
If you want to help VRM's a bit, place a fan blowing air onto them, that helps a lot for boards with no VRM heatsink.
 

marcUK2

Member
Sep 23, 2019
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If you want to help VRM's a bit, place a fan blowing air onto them, that helps a lot for boards with no VRM heatsink.
Had a look on ebay, and I can buy 10 mini heatsinks for next to nothing, then I guess I can epoxy them on with something like this

Do you think its worth it?
 
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lightmanek

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Feb 19, 2017
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Had a look on ebay, and I can buy 10 mini heatsinks for next to nothing, then I guess I can epoxy them on with something like this

Do you think its worth it?
Yes, it will help for sure, just don't expect hugely different OC results only from better VRM cooling. This will help prologue life of your board, and definitely stop CPU from thermal throttling induced by VRM overheating.
I did many ghetto mods in my days, revamping board or GPU cooling all the way back in AMD K6-2 days to this day. I never had a blown unit just from heat and I feel it is largely thanks to over sizing my cooling for the job.
Heck, I did the same with my BMW, where engine cooling is ready for 1000HP+ almost from the start of my tuning journey, but only now, after 4 years I'm getting really close to the real 1000HP power output. That from a 3 litre N54B30 engine with stock internals and 310000km :D
 

marcUK2

Member
Sep 23, 2019
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Out of interest, are the PPT TDC EDC values common across all motherboards with this 105W rated chip or are manufacturers setting their own limits for operation.?

In RyzenMaster, the TDC and EDC meters turn red (98-100%) under benchmarking even at stock, is this normal?

I checked the ASUS compatibility list, and the 3950X is listed as supported....Im guessing at the max capability of this board.
 

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