I've just tried the brand new SilverStone as a more powerful replacement for my (already) powerful Twister Storm from Enermax. The fan install went well, albeit a bit tight on the frame as a 140mm - for information it's a snug 4-pin PWM. Then sometime after the boot sequence, I'm going the dreaded bip and the RPM drop as well as hashing. I can't understand as the new fan being more powerful by a good +20 CFM with superior static pressure. I'm not planning to use them on S5 but on my forthcoming S7 and I'm concern that it will not work properly on the new unit.