Question Passive Cooling PC project seems to throttle early in Cinebench ?

[Dagenheim]

Hi,
I have an Hdplex H5 that I've modified with additional heat pipes and connected to cooler mounts, just a personal project trying to get more passive cooling power. My prior experience is building a Streacom DB4, which has been running nicely for a year now, and I just like the idea of passive cooling. I'm having a problem with higher wattages causing apparent thermal throttling before even reaching 90c, and I can't figure out what is happening.

This H5 as I've modified it steadily dissipates about 115 watts @87c running Cinebench with fully saturated heatsinks. But if I run the test again when it's hot, or increase my wattage, it'll run normally for a few minutes and then the power levels jump around, 65, 75, then boost back to limits for a few seconds. Using HWMonitor to watch, numbers more or less match Throttlestop's temps. It is also reporting temps in the 80's for CPUTIN and TMPIN3 under load, equal to CPU temp. This all happens with or without voltage offset. Pl1 115w, PL2 125w, Tau 10 seconds.

Most info I find always has to do with other cooling systems so it's been really hard to troubleshoot problems, help solving this would be much appreciated. It's probably something simple I don't understand.

Hardware:

I7 10700k
Asrock Phantom z490 atx
Kingston Fury 16gb 3200
Samsung 970 Evo 250gb
Silverstone Nightjar 450w

 

[Lutfij]

Welcome to the forums and a Happy New Year, newcomer!

Google'ing this;
Asrock Phantom z490 atx
brings up these boards;
https://pg.asrock.com/mb/Intel/Z490 Phantom Gaming 4/index.asp

https://pg.asrock.com/mb/Intel/Z490%20Phantom%20Gaming%204SR/index.asp

https://pg.asrock.com/mb/Intel/Z490 Phantom Gaming 4ax/index.us.asp
Which one do you have of the three that I've listed above? Or is it another SKU?

As for your predicament, something tells me it's not the CPU or your cooling of the CPU...more likely the heat built up within your VRM's on the motherboard. I'd try and strap a small Noctua fan on the VRM heatsinks and see if you're able to sustain the tests even after the cooling solution has been heat soaked(meaning that you've ran the test once already without leaving the opportunity for the heatsinks to return to close to ambient).

 

[Dagenheim]

Welcome to the forums and a Happy New Year, newcomer!

Google'ing this;
Asrock Phantom z490 atx
brings up these boards;
https://pg.asrock.com/mb/Intel/Z490 Phantom Gaming 4/index.asp

https://pg.asrock.com/mb/Intel/Z490%20Phantom%20Gaming%204SR/index.asp

https://pg.asrock.com/mb/Intel/Z490 Phantom Gaming 4ax/index.us.asp
Which one do you have of the three that I've listed above? Or is it another SKU?

As for your predicament, something tells me it's not the CPU or your cooling of the CPU...more likely the heat built up within your VRM's on the motherboard. I'd try and strap a small Noctua fan on the VRM heatsinks and see if you're able to sustain the tests even after the cooling solution has been heat soaked(meaning that you've ran the test once already without leaving the opportunity for the heatsinks to return to close to ambient).

I believe it is the first motherboard on your links. I have been able to watch the VRM warning in Throttlestop, and it stops when I blow a fan over them so that is exactly what is happening, thank you.

I've strapped some heat pipes to the VRM and connected them to my 4th cooler. It solves the problem at 115w but throttles after 15 mins at 120. Otherwise the rig looks capable of cooling maybe 125w. I never considered that the VRM sinks would overheat without airflow at higher wattages, going to be an extra problem in my next one. I'm aiming for 200w passive.

 

[Lutfij]

Passive would mean a higher fin density or surface area count. The advertising material states that the case can do 125W but I'm somewhat certain that they placed a fan on either side of the case(which are effectively the heatksinks/radiators, to aid in convection currents and effectively reach that 125W mark.

To also add on the VRM matter, I'm fairly certain that a higher priced motherboard with a lot more higher VRM quality would net you better results when going through a passive setup, however you need to understand that the heat soak will happen and the VRM's will eventually give out. Passive is not the route to take with that board/processor combo or anything from Intel until they get their plans in order.

 

[Dagenheim]

Passive would mean a higher fin density or surface area count. The advertising material states that the case can do 125W but I'm somewhat certain that they placed a fan on either side of the case(which are effectively the heatksinks/radiators, to aid in convection currents and effectively reach that 125W mark.

To also add on the VRM matter, I'm fairly certain that a higher priced motherboard with a lot more higher VRM quality would net you better results when going through a passive setup, however you need to understand that the heat soak will happen and the VRM's will eventually give out. Passive is not the route to take with that board/processor combo or anything from Intel until they get their plans in order.

I will try one of the boards with better dedicated VRM cooling. I know Intel isn't the best choice for this, I figure if I can get them to work then AMD should perform a lot better in the same system.

I do have additional surface area. On the top level of the H5 there are a few large coolers secured to a framework that I've connected with heat pipes laid over each other on top of the copper CPU block. It doesn't spread heat to the top layer of pipes very well, but I have a lot of ideas on improving the spread of heat for my next version. Just something I'm doing for fun while I try to teach myself more about computers, don't know if it'll amount to anything.