Safe Temperatures For VRM When Using A Locked Processor

[TheNamelessOne]

Hello everyone, I have a question about what would be the safe temperatures for the VRMs in my case.

I have a Gigabyte Z370HD3P with a i7 8700 non-K so no OC at all in a Fractal R6 case with the fans left in their default position. I've set the fans to run at all times and slowly ramp up as temps get higher and I'm not sure how to set the rear fan because by default my motherboard assigned it to the vrm sensor and it get really loud really quickly. Those Fractal fans are not as silent as they say they are.

 

I've noticed that the temps for the VRMs at least when running prime95 hits 85C and maybe if I let them it will go higher. The question is what are some safe temperatures for the VRMs to operate at?

Because I've searched a bit today and even here on this forum granted posts from some time ago, people say contradictory things. Some say keep them under 80C at all times, some say 100C is normal for them, some 125C is still within spec and some say even 150C is ok for VRMs. From 80C to 150C that's a huge gap. So what is it? What would be some safe idle temps and load temps? Or does that depend from motherboard to motherboard? Should I be worried? Or since I'm using a locked processor it just doesn't matter?

 

Oh and I've found this on a review of the board "The motherboard is in a 4+3 phase VRM, and it uses zero doubling. It uses the Intersil ISL95866 PWM controller in 4+3 mode. It adds multiple ISL6625A on the CPU and iGPU rails to enhance phase count. The CPU VCore VRMs use double the number of MOSFETs per phase, while the iGPU phases use the standard number. On Semiconductor NTMFS4C06N is the low-side MOSFET, and the NTMFS4C10N is the high-side MOSFET for each of the power stages.

The memory VRM uses a Realtek RT8120D for a single phase PWM with driver and then three On Semiconductor NTMFS4C06N in a two-low one-high MOSFET configuration. More Realtek RT8120 controllers are used for the VCCSA and VCCIO rails." <This is something beyond my understanding.

 

Thanks in advance. 

 

 

[Fasauceome]

22 minutes ago, TheNamelessOne said:

Some say keep them under 80C at all times, some say 100C is normal for them, some 125C is still within spec and some say even 150C is ok for VRMs. From 80C to 150C that's a huge gap. So what is it?

According to Gamers Nexus, VRM temps under 125 are a-ok, and many VRMs are safe under 150 

 

It's not a semiconductor so the 100° Celsius cutoff point for your CPU doesn't apply here

[Jurrunio]

The silicon inside most mosfets in computers are good for up to 150C, which leads to about 125C on top of the package (the casing basically). What's no good for that are the capacitors around the VRM, those are rated for 5000 hours at 105C usually, high end boards do more but low end boards can be as bad as 2500 hours at 105C or 5000 hours at 80C, and capacitor lifespan shortens exponentially with temperature. If your mosfets are running at 100C, then the capacitor should be anywhere from 60-90C depending on their location, airflow and heatsink design which is why I recommend that temperature to be the max.

 

However there are many cheap boards where the thermistor (as temperature sensor) is not located where it should be, as a result not reading mosfet temperature properly. That's why you should take its reading with a grain of salt.

 

The heatsink on this board looks ok, I wouldnt' worry too much about it in your setup.

28 minutes ago, TheNamelessOne said:

It adds multiple ISL6625A on the CPU and iGPU rails to enhance phase count.

Nah that's just a driver IC, not a doubler and does not increase phase count.

[TheNamelessOne]

@Fasauceome And @Jurrunio Thank you both. Good to know that I'm ok, I got a bit worried when I ran prime95 and saw the temps hit 85C, so I entered panic mode a bit.  

 

[Penpilot]

@TheNamelessOne thank you random stranger for asking the same question 3 years before me

[Beerzerker]

57 minutes ago, shreshta said:

@TheNamelessOne thank you random stranger for asking the same question 3 years before me

And we'd like to express our thanks for the necro....