How hot is to hot for VRMs?

[smartroad]

I have a Gigabyte AB350 Gaming 3 motherboard running a Ryzen 1700 OC'd to almost 4GHz (about 50MHz off annoyingly!). Using HWInfo I have seen that my VRM can quickly reach temps in excess of 100C when synthetic benchmarking/stress testing. I have been able to 3D print a mounting bracket for an 80mm fan to point towards the VRM 'heatsink'. That gets it down to about 80C-ish. Under normal use it hovers around 60C in games etc.

 

I have setup Gigabyte's fan control to only switch the 80mm fan on when the VRM hits high temps, otherwise the fan i have is somewhat noisy.

 

Given that with no fan it is reaching (and breaching) 100C is that bad? I feel it should be bad!

[mariushm]

The mosfets (the main components in the VRM) are designed to function properly up and for infinite amount of time to 125c or 150c (a lot of them can safely do 150c, but the majority of them have recommended maximum temperature of operation at 125c).

However, their peak efficiency is somewhere a bit lower than that, at around 80c. . 

Also, motherboard manufacturers choose to configure some thermal limits at around 110c and generally design the heatsinks or pcb (heat radiates through pcb also) to stay below 100c.

If a motherboard's circuit board stays above 100c for long periods of time, the fiber glass and glue in the circuit board will eventually be affected (degraded) and the quality of the circuit board will decrease and eventually the board can be damaged.

If you only get 100c in benchmarks and synthetic stuff, then you're probably fine.  60c in games is absolutely fine, no need to waste your time with fans.

[Jonathan Lemmens]

2 hours ago, smartroad said:

I have a Gigabyte AB350 Gaming 3 motherboard running a Ryzen 1700 OC'd to almost 4GHz (about 50MHz off annoyingly!). Using HWInfo I have seen that my VRM can quickly reach temps in excess of 100C when synthetic benchmarking/stress testing. I have been able to 3D print a mounting bracket for an 80mm fan to point towards the VRM 'heatsink'. That gets it down to about 80C-ish. Under normal use it hovers around 60C in games etc.

 

I have setup Gigabyte's fan control to only switch the 80mm fan on when the VRM hits high temps, otherwise the fan i have is somewhat noisy.

 

Given that with no fan it is reaching (and breaching) 100C is that bad? I feel it should be bad!

100C is kinda living on the edge, these mosfets die without warning above 132C , but their efficiency at 105C or above is so bad that they probably will not power an 8 core CPU especially with an OC. I would advise to keep that 80mm fan in there.

 

In this video you'll find a bit more info about everybody's VRM implementation on B350, Gygabyte is at 14:10 minutes.

 

[mariushm]

9 minutes ago, Jonathan Lemmens said:

100C is kinda living on the edge, these mosfets die without warning above 132C , but their efficiency at 105C or above is so bad that they probably will not power an 8 core CPU especially with an OC. I would advise to keep that 80mm fan in there.

 

In this video you'll find a bit more info about everybody's VRM implementation on B350, Gygabyte is at 14:10 minutes.

 

He only gets 100c in synthetic benchmarks and programs that abuse the overclocked CPU.  He says in games the temperature is around 60c

 

I'd say below around 85c there's no point in doing any changes - if your temperature sits below 85c for 95% of the time or more, then let it go.  Games and even apps won't abuse the cpu as much as synthetic benchmarks do.

 

No need to scare the guy pointlessly.

[Jonathan Lemmens]

9 minutes ago, mariushm said:

He only gets 100c in synthetic benchmarks and programs that abuse the overclocked CPU.  He says in games the temperature is around 60c

 

I'd say below around 85c there's no point in doing any changes - if your temperature sits below 85c for 95% of the time or more, then let it go.  Games and even apps won't abuse the cpu as much as synthetic benchmarks do.

 

No need to scare the guy pointlessly.

You're right, and it wasn't my intention to scare people.

But I like to pass my benchmarks with flying colours, so that means low temps as well. Also VRM efficiency is directly linked to the temp of the mosfet, so the lower the temps the better.

The difference in power draw during a stresstest vs during games is just the extra "safety margin" to me. I would never do a benchmark and tell myself: "it's kinda running out of spec now, but when I'm gaming it'll be back in spec so it's fine".

[smartroad]

Cheers guys. I thought that VRM's could run hot without much issue - compared to other parts anyway.

 

@Jonathan Lemmens, I get where you are coming from ans understand the warning. As it stands I will continue as is, the fan helps keep the temp down even under synthetic tests for now. Eventually I may upgrade the mobo to allow more headroom in the future though.

 

I was considering looking at the heatsink and having a custom one machined (have access to someone who could help) that has many more vanes to allow for more efficient heat transfer.