Question LGA 1700 12th gen CPU bracket won't fit in case?

Jun 28, 2022
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Hi all,

I've been building computers for decades, but only recently upgraded to a 12th gen Intel processor - I think it's the first time I've had a CPU cooler where you had to put a bracket on the back of the motherboard and screw the cooler into it.

This is the cooler I bought:

https://www.scan.co.uk/products/arctic-freezer-i35-cpu-air-cooler-120mm-pwm-fan-54x-aluminium-fins-4x-copper-heatpipes-intel-1700-12

I have a 19" rack at home with my machines in, so I went to fit my new setup into a rackmount server chassis. It's one like this:


The motherboard simply won't fit in the case - the cooler bracket presses against the motherboard mounting plate. If I try to screw the motherboard down onto the mounting posts, it'll bend the mobo.

So I have a Fractal Design Define R5 case, and I notice it has a giant cutout in the motherboard mounting plate that allows the cooler bracket to fit nicely. Eg:

https://static.tweaktown.com/content/6/8/6834_17_fractal_design_define_r5_mid_tower_chassis_review_full.jpg

I built my new computer into this case and everything fits, and works, perfectly.

Now I'm looking for a rackmount case that has a similar cutout.. and I can find literally none that have this cutout. I'm wondering if I'm not understanding something, or I need a different bracket/cooler combination? Searching the web I can't find anyone who's had the same problem as me, which makes me think I'm not doing something right. Maybe I just need taller motherboard mounting standoffs?

Can anyone help?

Thanks!

Chris.
 

tennis2

Judicious
The mobo tray on a case either has a CPU bracket cutout or not. Certainly nothing preventing you from installing the cooler WITHOUT the rear bracket either. Just know that the bracket is there to distribute the load from the bolts out to a greater surface area of the mobo.
 
Jun 28, 2022
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The mobo tray on a case either has a CPU bracket cutout or not. Certainly nothing preventing you from installing the cooler WITHOUT the rear bracket either. Just know that the bracket is there to distribute the load from the bolts out to a greater surface area of the mobo.
Thanks for the reply. What I'm finding really confusing is that you would expect PC case specs to say whether the motherboard tray is compatible with LGA 1700 brackets or not. I've been searching for a week now, and I haven't found a single rackmount case that actually makes this distinction, and most photos of the cases make it impossible to see if a cutout exists. I thought I was missing something really obvious.

Interesting you mention installing the cooler without the rear bracket... I'm guessing there are specific coolers that work like that? The cooler I have only had screws for the bracket.
 

geofelt

Titan
The cutout on normal cases is there primarily to allow a cooler to be mounted or remounted without the need to remove the motherboard from the case first.

I think you can resolve your problem by putting a couple of washers between the motherboard and the server case.
You may need to use longer than normal screws to attach the motherboard to the case.

Many stronger LGA1700 coolers are designed to use a backplate.
I would avoid other fixes, Lga1700 needs to be able to put proper pressure on the cooler mount.

What cpu are you trying to install?
Many intel processors will come with a standard pushpin cooler that does not need a backplate.
 

tennis2

Judicious
you would expect PC case specs to say whether the motherboard tray is compatible with LGA 1700 brackets or not. I've been searching for a week now, and I haven't found a single rackmount case that actually makes this distinction,
The LGA1700 spec is really just the CPU cooler hole pattern on the mobo. It has nothing to do with the ATX standards of a case. Every cooler manufacturer designs their own backplates if they're included in the kit.

AMD mobos come with a backplate installed, so most coolers are designed to just bolt to the stock AMD bracket. So that's nice for case manufacturers to be able to plan for that (albeit most modern case mobo trays just have a cutout anyway)
 
Jun 28, 2022
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Thanks all for the replies.. so I guess it's more like the backplates for the CPU coolers are just generally manufactured assuming the motherboard backplates have a cutout, and what I'm really looking for is a CPU cooler backplate with a low enough profile, rather than a rackmount case with a cutout?

I think it's time to take @tennis2 's advice and get the Dremel... washers might also do it, but it's quite a few mm too big at the moment.

Thanks again!
 

tennis2

Judicious
Out of curiosity, how thick is the backplate that came with your cooler? Just off memory, I feel like most of the backplates I've used were maybe....4mm thick. Google says that standard standoffs are 6.5mm.
 

Karadjgne

Titan
Ambassador
It's not just the backplate, it's also screw direction. Some back plates have nuts built in or movable, the screws inserted from the front, so by necessity stick out further than the backplate, could easily see a total of 7-10mm. Some are flat on back with screws sticking through the motherboard from behind, so flush or less than the backplate.

Standoffs come in a variety of sizes, ATX standards require a minimum of 6.5mm. But you can get 4mm to 25mm easy enough, so doesn't require extreme measures such as chopping out the motherboard tray with a dremel or using washers with longer than standard 6/32 or M2/M3 screws, which can possibly bottom out if the threads are a hair too long. Most standoffs should be used with the paper washer for just that reason.

If there's room for the cooler, I'd get a set of 10-12mm standoffs and use those instead, with the paper washers and screws to match.
 
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Karadjgne

Titan
Ambassador
Longer standoffs would change the position of the rear IO cluster compared to the cutout in the back of the case.
Ahh, true. Forgot about that minor detail lol. Well that blows that idea, looks like dremel to the mobo tray is the last remaining option. Followed by a good filing, cuz that cut edge will be sharper than a fish-wives tongue.
 
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