I can't believe this... A couple of weeks ago I purchased a brand new M4 512GB from Amazon but when I installed it into my MBP I noticed a barely audible noise coming from it when under load. I don't know how to describe it, it's like a very faint screeching noise, or should I say some sort of noise that indicates that the SSD is working. I started hearing the noise right from the start, while installing Mountain Lion from a USB stick. You have to be in a quiet environment in order to hear it, but the thing is you can hear it, although barely. However, if you place your ear right to the MBP, it's slightly more apparent. Anyways, last week I contacted Crucial and they agreed to send me a replacement, which I received yesterday. I installed it today, but the noise is still there. What are the ODDS that 2 SSDs from completely different sources would have the same error?!?! (The 1st SSD was purchased from Amazon US, and the replacement came from Crucial UK because I'm in Europe as we speak). I'm 99.99% sure it's not the fans making the noise and the noise is definitely coming from the SSD bay. Any ideas what could be the problem? I mean, there shouldn't be ANY noise whatsoever coming from an SSD. Crucial technician suggested I do two things: 1. Try downgrading to 0309 firmware (he said 000F was not meant for Macs in the first place, and 010G is only recommended for people who experienced issues described in 010G change log) --- I plan to downgrade in a min and I'll report back, though I don't really think it'll help. 2. Try my SSD in a different computer or an SSD caddy to see if it still makes sounds there. This is really frustrating as I can't really afford to spend so much time on this testing. Could it be my MBP's hardware problem? UPDATE 1: downgraded the firmware, but as expected not much change... Can still hear some noise when under load (BlackMagic test for example).