Question Cooler + Fans MB Weight Limit?

[Mantrid-Drone]

I've not found anything about this on the Gigabyte or any other MB manufacturers' web sites I've look at about the recommended maximum weight of coolers (plus the fans). They only seemed concerned with the height, the dimensions, CPU mount compatibility and whether it clears the RAM.

In particular I'm looking at the Noctua NH-15S and its more recent iterations which vary between about 1Kg and 1.5Kg depending on the number of fans. This Noctua type of cooler is shown as compatible with the Gigabyte MB I'm going to use (B760-DS3H LGA 1700 CPU mount) which doesn't appear to be different from any other ATX MB I've ever seen or used.

The unsupported Google AI search result when asking this question states weight limits for MB, not specifying the type and therefore likely unreliable information, as generally being around 1Kg. Yet Noctua who know what they're doing are manufacturing CPU air coolers whose total weight in their supplied configuration is actually slightly over 1.5Kg. Why would they do that if a MB can't actually handle that weight?

Does anyone here know anything for certain about this matter?

 

[mindless1]

Do those heatsinks come with a reinforcement backplate for behind the socket? If not, I'd wonder if you really need a cooler that heavy, but on the other hand the makers of the cooler had to - just HAD TO have tested their heatsink on some motherboards before qualifying the prototype for mass production, so I think it'll be fine as long as you follow their installation procedure correctly, and take the heatsink off if the system is going to encounter rough transportation.

 

[Mantrid-Drone]

That transportation matter, although it won't apply for me, is actually something the Google 'research' mentioned too. It suggested a weight 20% - 30% less than 1Kg if the PC is going to be moved any distance.

But that would put a lot of other quite modest coolers into the 'too heavy' bracket like the CoolerMaster Hyper EVO 212 which, with an extra fan, weighs in at 750+gms.

The Noctua NH-15S installation instructions mention that they recommend detaching the cooler before transportation and they won't be liable for any damage if you ignore that advice.

No addition reinforcement plate with the NH-D15S that I can see. It comes with a robust mounting system and an AMD specific replacement backing plate but no reinforcement.

The Gigabyte MB backing plate looks quite substantial but the leverage force of a 1.5Kg weight acting through 160+mm is a significant force on the top and bottom edges of the plate pulling and pushing against the MB itself.

You'd think that all parties involved ie. the MB and cooler manufacturers and whoever designed the LGA1700 mount spec would all be on the same page but are they?

 

[mindless1]

You could contact Gigabyte and ask them, though it wouldn't surprise me if they just took the conservative approach and stated to use a lighter cooler without actually looking at any engineering data to qualify the statement, and it might not be realistic to expect them to test every board with every new cooler that hits the market, then there's the variables of pre-existing stress on the board from a less than perfectly true case mount, even standoffs that weren't completely screwed in.

I suppose one thing you could do is just order the cooler, have the motherboard out of the system and very carefully mount it, carefully hold the board propped up vertical on a table and use a straight edge aka ruler to see how much the board is flexing, then decide if you're comfortable with that... but then if it breaks something doing that test, it wasn't such a good idea. On the other hand if Gigabyte clears it as usable, document that, then if it breaks, at least you have that.

I still wonder if you *NEED* that massive a heatsink. If not, why fight an uphill battle? I also still assume it will work fine since Noctua lists it as compatible, though there can be some differences in rigidity from one board to a next, whether due to using a tighter fiber weave or other differences in the PCB material used, or proximity of adjacent rigid features using through-hole solder joints, like memory or other slots that will stiffen the board near them.

If you're going to be doing mad-overclocking, then I'd also wonder about flex on the board potentially decreasing contact effectiveness of the heatsink on the row of 'fets to the left of the CPU socket on many boards including the one you mentioned. An infrared heat gun could be used to track board temperature at various spots near the fets. Then again if that heatsink is screwed down instead of using spring loaded push pins, that will increase rigidity on that side of the socket as well and decrease any chance of flex causing reduced 'fet-heatsink contact.

The easier answer would be to lay the system on it's side or use a case that mounts the board horizontally, then put a rubber bumper (stick-on adhesive type placed where the case board mount backplane doesn't have holes in it like so many do now) of the right height, directly under the center of the socket or strategically placed around the area to take up the extra weight and prevent board flexing. Again this probably isn't necessary, just to take the sink off when transporting the system. I would do that with any vertically mounted (typical) heatpipe based 'sink, not just one that heavy. I mean if doing more transportation than carrying it by hand, room to room.

 

[bba-tcg]

I would think that the weight of the heatsink wouldn't really be that important of an issue if a backplate was used for mounting re-enforcement. Considering that modern motherboards already have a backplate for the bottom of the motherboard solely for the socket, the additional backplate for the heatsink should be more than sufficient, That said. some amount of common sense should still apply, This theory (of mine) may be the reason there's not a lot of data concerning weight limits - because I highly doubt that my theory is novel or unique.

As for transporting, I believe the graphics card should be removed and the PC positioned so that the heatsink is above the motherboard - so, in essence, for most cases, laid on its side with the motherboard at the bottom..