I haven't done any major overclocking on my Pi3B, but under load these heatsinks have helped keep temperatures noticeably low. The glue on them made the heatsinks slide a bit after application. Maybe they got stronger after a while? I didn't want to put too much strain on them in case they fall off. My Pi is currently at a 90 degree angle and they work great in that orientation.
Heatsink for SSD ESPADA ESP-R1, black
13 Review
Cooler ID-Cooling SE-224-XT White (Intel LGA2066/2011/1200/1151/1150/1155/1156// AMD AM4)
26 Review
Netac NV7000 NT01NV7000-1T0-E4X SSD, M.2, 1.0Tb, PCI-E x4, Read: 7200 Mb/s, Write: 6800 Mb/s, 3D NAND, 1400TBW, NVMe
11 Review
Samsung 970 EVO Plus 1TB SSD? NVMe M.2 SSD
31 Review