Hello,
my screws are a little bit too long, 1-2mm and I would like to know WHICH exactly dimensions I need.
I have the RockPi 4 with the big Passive Cooler.
Which screws do I need for the Radxa passive cooler?
Practically impossible to find the small hex ones are m2.5x 3mm which is prob why they break as often minimum thread length is 3mm.
Try doing a search for m2.5 laptop screws and I have come to the conclusion its easier and better to get a 1mmx20x20mm copper shim and use m2.5mm washers as spacers.
Just shows how good the people at Radxa are.
I don’t mean it in a good way, tbh I would take the RaspberryPi 4 if I could go back in time.
Raspberry 4 isn’t better I have one on my desk.
All cases no longer fit and you have to have active cooling as it thermal throttles all the time.
In fact its a £1 only weekend on Ebay and my RaspberryPi4 will be on there.
Pi4 is the worst raspberry to date the Pi fan boys go on about every thing just works which why this Pi is up for sale as its just not true.
The main problem with the Pi is VC4 and the vulnerable falling for what is essentially Raspberry snakeoil 4K is hillarious as it can not even playback 1080p in its chosen browser of Chromium.
I suggest you actually own a Pi 4 and use a Pi 4 and not just believe much of the hype that generally reaches levels of total BS.
Its why Raspberry panicked and released the ‘not until 2020’ product which has damaged them further, but they are panicking not just because of the RockPi4 but several Arm SoC SBCs have or are approaching 100% mainline linux status.
The Raspberry Pi 4 should of blown the Rockpi4 out of the water but failed as the CPU without thermal throttling still lags by 20-30% but its GPU is an atrocious 200% down on the Mali-T860MP4.
Panfrost & Mali completly kill VC4 and there isn’t a Broadcom answer apart from snakeoil marketeering.
The CPU is lacklustre but the GPU makes it impossible for it to be a desktop replacement unlike the RK3399 that will even run Gnome desktops with a push but certainly much more than raspberries attempt at a desktop.
Raspberry is the Apple of the SBC world that goes against opensource mantra as there ecosphere for many reasons is locked in.
I have also received screws that are too long with a heatsink that was recently bought in Poland (PD: 2019-04). Looking at your nickname it is possible that we bought it from the same distributor 
so probably a bad batch.
I worked around it in a similar way that @stuartiannaylor did. I put a 1mm copper pad on the cpu package but did not put any washers as I do not have any fitting right now. Now the only point of support is the cpu package and the screws are carefully screwed to make a best balance but the overall solution took some time tweaking and is surely not optimal from mechanical point of view
I also bought an acrylic case but it turns out I cannot use the top part of it with large heatsink on the bottom.
It would be good if someone at @radxa looked into that and verified the contents of the packaging in current batches as there may be more people receiving large heatsinks with screws that do not fit the smaller standoffs. I am pretty satisfied with my Rock Pi 4b but agree that those little things can spoil the fun for many people.
M2.5mm washers are .5mm thick I think.
But do agree as those little things are so little but make huge impression on the overall product.
PS cheap Pi4 on ebay this Sunday with offical 5.1v psu, piminori heatsink & a1 sd.
If your screws are too long, either fill the difference with washers, or file it shorter.