mITX Boards & HSF Weight Limitations

[Lady Lumps]

Hello everyone!

I've been doing custom ATX builds for many years now, but I'm new to the mITX scene. I mention this because, while it may be generally acceptable (though morally questionable) to put a 4 pound monster like the Thermalright TRUE Copper on a thin piece of silicon formally known as an "ATX board", I doubt the same goes for its mini cousin. Granted—as irony would have it—AnandTech's very own Ian Cutress did just that, along with some guy on YouTube, but both of these were done in open test bed environments. Weighing in factors like long-term usage, mobility, vertical motherboard orientation, a whopping 4-fastener configuration, and, well... gravity, I suspect would deter such ventures.

Now I don't have anything other than common sense to back my suspicions, failed Google attempts notwithstanding, as not even the official mini-ITX spec sheet knows what the skinny is on weight limitations. Having reached my intellectual limitations, I thought I'd go to a place where kindhearted, tech-savvy geniuses, ready to lend a hand absent regard for monetary gain are a dime a dozen. But Geek $quad was closed and so now I'm here... :awe:

Short story long, what's the fattest heatsink I should put on an mITX mobo?

I'm not looking for anything official like a documented figure or even a de facto standard, but more of a "best practice" cutoff point.
Here are some heatsinks and their respective weights for reference:

Intel Stock Cooler (E97378-001): 280g
Noctua NHL-12: 415g (w/o fan)
Cooler Master Hyper 212 Plus: 626g
Tuniq Tower 120: 798g (w/o fan)
Intel Aftermarket Retail Cooler (XTS100H): 885g
Thermalright HR22: 1120g (fanless)

Admittedly, motherboard orientation is the heaviest of all factors to be considered, and although I'm all for answers that apply to my particular setup, I'm sure more would benefit from a broader, less specific approach. However, for those of you with time limitations, here's what I have in mind:

Motherboard: ASRock Z97E-ITX/ac
Heatsink: Phanteks PH-TC12DX (743g w/ 1 fan)
Case: Antec ISK600 (Horizontal board orientation w/ 170mm CPU HSF clearance)

Any guidance is much appreciated!
​  

 

[BonzaiDuck]

Hello everyone!

I've been doing custom ATX builds for many years now, but I'm new to the mITX scene. I mention this because, while it may be generally acceptable (though morally questionable) to put a 4 pound monster like the Thermalright TRUE Copper on a thin piece of silicon formally known as an "ATX board", I doubt the same goes for its mini cousin. Granted—as irony would have it—AnandTech's very own Ian Cutress did just that, along with some guy on YouTube, but both of these were done in open test bed environments. Weighing in factors like long-term usage, mobility, vertical motherboard orientation, a whopping 4-fastener configuration, and, well... gravity, I suspect would deter such ventures.

Now I don't have anything other than common sense to back my suspicions, failed Google attempts notwithstanding, as not even the official mini-ITX spec sheet knows what the skinny is on weight limitations. Having reached my intellectual limitations, I thought I'd go to a place where kindhearted, tech-savvy geniuses, ready to lend a hand absent regard for monetary gain are a dime a dozen. But Geek $quad was closed and so now I'm here... :awe:

Short story long, what's the fattest heatsink I should put on an mITX mobo?

I'm not looking for anything official like a documented figure or even a de facto standard, but more of a "best practice" cutoff point.
Here are some heatsinks and their respective weights for reference:

Intel Stock Cooler (E97378-001): 280g
Noctua NHL-12: 415g (w/o fan)
Cooler Master Hyper 212 Plus: 626g
Tuniq Tower 120: 798g (w/o fan)
Intel Aftermarket Retail Cooler (XTS100H): 885g
Thermalright HR22: 1120g (fanless)

Admittedly, motherboard orientation is the heaviest of all factors to be considered, and although I'm all for answers that apply to my particular setup, I'm sure more would benefit from a broader, less specific approach. However, for those of you with time limitations, here's what I have in mind:

Motherboard: ASRock Z97E-ITX/ac
Heatsink: Phanteks PH-TC12DX (743g w/ 1 fan)
Case: Antec ISK600 (Horizontal board orientation w/ 170mm CPU HSF clearance)

Any guidance is much appreciated!
​  

The all-copper version of the TRUE may have tickled someone's fancy, and I never heard any stories of disaster. Personally? I think 4 lbs is too heavy.

But let's be a bit more meticulous about our topic here. Does the weight of the copper TRUE include the weight of the fan(s)? Whether it's that version of the TRUE cooler or something else, your average 120x25mm fan or 140x25mm fan weighs about 6.5 oz. Two of them adds up to more than 3/4 lb.

But forget the copper cooler. And don't forget that this isn't about weight: it's about torque, and an equal determinant of torque in our example is the distance from the motherboard to a center-of-gravity for the pipes and fins of a cooler. Much of the weight is in the heatsink base, and that weight makes for very little stress on motherboard PCB -- it's torque is near zero.

I wouldn't have a problem hanging an NH-D14 fan from an m-ITX motherboard, but it has to fit in your case. There are other options that offer effective cooling with the same heatpipe technology.

If I were worried about "weight" (torque, really) I'd find a way to use the case exhaust fan to draw air exclusively from the rear of the CPU cooler, or avoid hanging more than one fan on the assembly. "None" would be ideal, and with some minor case mods and a choice of brackets, you could have "push-pull" fans on the cooler with fans mounted to the case -- front and back.

An mITX motherboard wouldn't be manufactured to be more fragile than an ATX motherboard. It's less likely that stress to a small board would cause any warpage, because of its size and tensile properties. Is it easier to bend a foot-long/foot-wide piece of cardboard, or a cardboard square 6"x6"?

Of course you solve the problem with a horizontal motherboard mounting, as you show in your picture(s). Frankly, for the size of the motherboard and the advantage of a compact PC, there's nothing wrong with that approach. I just don't think there's a "problem to solve" that requires it -- unless, of course, you want to use the NH-D14/D15 and hang three 120x38mm 12Vx2A high-power fans on it.

 

[Lonyo]

Se the iPhone debate. Bigger surface = easier to bend.

But as noted, the footprint of a horizontal mITX is small enough that many cases are set up like that anyway, and not vertical, so the weight is a non-issue.

 

[mistersprinkles]

IT'S FINE!

You can put any heatsink that fits your case on your motherboard. NHD15 even (much heavier than a TRUE). There's a guy on the other forum I go on who has an NHD15 on an ITX board and no problems.

If anything it would be a bigger problem on an ATX board than an ITX board- bending due to weight stress, due to larger surface area. Look at how an iphone 6 plus bends vs an iphone 6. More surface area= easier to bend.

PCB's from given OEMs are all about the same thickness. Gigabyte UDX boards are thickest, and it goes from there. Whether ASUS puts out an EATZ Z97 board or an mITX Z97 board that PCB will be the same thickness. DOn't worry about it.

 

[dave_the_nerd]

Dadgummit, now I'm getting all nostalgic for the MCX-462U. That was a heavy beast in its day.

Personally, I wouldn't want to go over 2 pounds (~900g) on anything vertically mounted, and anything heavier than a pound, I'd remove before shipping just in case. Personal preference - I have no data to back that up.

The screw-through mounting of most HSFs now makes me happy. That was a big deal on the old Swiftechs - some motherboards didn't even have mounting holes. WE ATTACHED OUR FANS UPHILL! BOTH WAYS! AND WE LIKED IT!

 

[Lady Lumps]

Thank you all for your input! It's nice to feel welcome in such a great community.

I noticed there's a common theme in most of your replies. And while I agree with it, I think there's a factor (albeit potentially moot or negligible) being overlooked here, that I very briefly mentioned in my original post.

Yes, greater surface area = easier to bend, naturally. However, we're not talking about free-floating objects here. Take that same iPhone 6 and bolt it down in each of its 4 corners. Then take the iPhone 6 Plus and bolt it down in each of its 4 corners AND in 7 other places, roughly even in distribution. Now which one is easier to bend?

Full ATX motherboards are secured on up to 12 different points, versus Mini-ITX being limited to 4. Sure, it can be argued that only 4 of those 12 are "relevant" to HSF support, and that since they are both part of the ATX form factor, not only are the locations of those 4 points respectively identical, but also, both CPU sockets are roughly in the same general area, seemingly making it one. giant. moot. point. Right? Maybe, maybe not...

Perhaps the strongest counterpoint is that, although both CPU sockets are indeed in the same, general area, the difference in distance from each HSF mounting hole to a motherboard standoff is relatively considerable between the two form factors. (The devil's in the details.) Since Mini-ITX boards have everything cramped within a smaller area and only 4 points of support, the DIMM slots (amongst other, less notable things) effectively push the CPU socket closer to the center of the board, and in doing so, greatly reduce the offload from its 2 closest supports. Whereas Full ATX motherboards can have as much as 5 points of support just along the center of the board, 2 being in the immediate vicinity of the CPU socket, on top of another 4 on the neighboring outside perimeter. Yielding a total of 6 points of support near the primary stress source, of which, 2 offload the weight (or torque) of the HSF almost exclusively.
 

Now I ask you the logically rhetorical question: Where is localized pressure most likely to give, towards the edge or dead center?

And to a lesser degree, there's also the fact that several motherboard manufacturers run passive heatsinks around the CPU socket perimeter on their Full ATX boards (more so than on their Mini-ITX offerings), making them even more resistant to warping or breaking. And yet, despite all of these favorable factors, there were still Full ATX boards that managed to warp. So I could only imagine how Mini-ITX would fare, minus these advantages. This thought is what concerned me and brought me here to begin with. In the end though, theory only gets you so far. In practical terms, this can all be simplified into one question:

Anyone out there hanging a 500g+ HSF from a vertically mounted mITX motherboard for more than a year?

I'd love to hear from ya! :awe:

IT'S FINE!

You can put any heatsink that fits your case on your motherboard. NHD15 even (much heavier than a TRUE). There's a guy on the other forum I go on who has an NHD15 on an ITX board and no problems.

Maybe you're thinking of the TRUE Spirit? In which case, yes, the NH-D15 is heavier by 120g. But I was actually referring to the TRUE Copper. Weighing in at 1900g for the heatsink alone, is almost double that of the NH-D15. Nonetheless, I get what you were trying to say. By any chance, do you know if that guy has his motherboard mounted vertically or horizontally? That would help quite a bit.

Dadgummit, now I'm getting all nostalgic for the MCX-462U. That was a heavy beast in its day.

Personally, I wouldn't want to go over 2 pounds (~900g) on anything vertically mounted, and anything heavier than a pound, I'd remove before shipping just in case. Personal preference - I have no data to back that up.

The screw-through mounting of most HSFs now makes me happy. That was a big deal on the old Swiftechs - some motherboards didn't even have mounting holes. WE ATTACHED OUR FANS UPHILL! BOTH WAYS! AND WE LIKED IT!

Ahh yes, those were the good ol' days... Speaking of nostalgia and questionable mounting mechanisms, can you guess what heatsink this is in the figure for step 2? I'll give you a clue: it's not a CPU heatsink. lol

 

[dave_the_nerd]

Ahh yes, those were the good ol' days... Speaking of nostalgia and questionable mounting mechanisms, can you guess what heatsink this is in the figure for step 2? I'll give you a clue: it's not a CPU heatsink. lol

Well, it's a northbridge heat sink, obviously. Don't be silly.

 

[Lady Lumps]

Haha! It's actually the

Spoiler

Zalman ZM-NB47J

.

It was my favorite NB heatsink back in the nForce2 days and a staple replacement for those annoyingly loud 40mm stock NB coolers in many builds since. And as long as you had a decent amount of unobstructed airflow in your case, it worked like a charm, sometimes even better than its actively cooled brethren. I just found it funny that it made an uncredited cameo appearance playing the part of a CPU heatsink, of all things. I don't think the illustrator was counting on someone being able to identify it as such. lol

Ain't she purty?

 

[BonzaiDuck]

[Bonzai's Note: Per folks using an mITX board with a 500gm cooler]

I'd love to hear from ya! :awe:



Maybe you're thinking of the TRUE Spirit? In which case, yes, the NH-D15 is heavier by 120g. But I was actually referring to the TRUE Copper. Weighing in at 1900g for the heatsink alone, is almost double that of the NH-D15. Nonetheless, I get what you were trying to say. By any chance, do you know if that guy has his motherboard mounted vertically or horizontally? That would help quite a bit.

It gets back to the source of the stress. "Weight" is simply that -- bearing down vertically on the retention bolts holding the "weight" (heatsink, etc.). The STRESS arises from the TORQUE, which is a weight applied at a distance from a pivot-point -- in this case, the heatpipes and fins, PLUS the weight of any fans. All that weight in pounds multiplied times a distance. The DISTANCE, for want of a calculus-problem/solution, measures from the motherboard to about half the height of the cooler.

There is a big chunk of weight in the heatsink base. But that weight has essentially 0 torque -- therefore, doesn't stress the mobo, since it bears down on the edge of the PCB. The PCB material is strong enough to easily support that weight at right angles to the board's surface.

The torque arises from the pipes, fins and fans. The pipes and fins for most coolers can't weigh all that much, but they WOULD for a COPPER "TRUE." So the "Pound-Feet" of the torque will stress the board. For a D14 or D15, that weight and its torque will be considerably less than that of the Copper TRUE.

If you're all that worried about it, like I said -- you can take the fan weight off the cooler, or only hang a single fan on it.

We're using single-fan Hyper 212 EVO coolers on mATX boards -- never had a problem. I might have worried about it and simply ducted the coolers to the exhaust fans, but didn't worry then (2008) and don't worry now.

Anyway, there are several low-profile heatpipe coolers probably more appropriate for an ITX motherboard. I might use an mATX or ATX board for my super-duper overclocked system. Maybe SOMEBODY wants to build that type of system with an ITX board. I wouldn't know.