I have a Dell One 24 (all-in-one),just under 2 years old, which has had a lot of "issues." First, HD went bad after 5 months, was replaced, and all was good until about 10 days ago. This time, freezes occurred frequently, chkdsk came up with different errors with each boot, supposedly fixed them, only to recur, and Dell Diagnostics came up with read errors. Dell replaced that HD, but it failed after a few hours and could not boot up, got strange error messages, among them "can't find kernel" and system itself would not recognize C:\ partition. Long story short, Dell support decided to replace both motherboard and hard disk.
Now, the computer seems to be functioning well except for one thing: As soon as I turn the computer on and before Vista starts to load (even after the system being shut down overnight), the noise from the system is very loud. I can feel the fans do come on immediately when the system is turned on--not normal behavior previously. This loud noise never goes away while the system is on. I never had a noise problem previously. Dell support acknowledged that something was wrong (I held my phone to the computer so they could hear it), but they did not know if it was disk "thrashing" or problem with the fans.
I noted the noise as soon as the last tech turned on the machine after replacing hard disk and motherboard, but merely assumed it would be some kind of temporary thing. The tech heard me say, "wow, that's loud," but did not comment and just left after verifying that installation had started properly.
I'm getting yet another Dell service call later this week. This time, they're sending replacement fans, yet another hard disk, and for good measure, new memory modules! It's really up to the tech as to which of these to actually install after looking at my system. Incidentally, as a test, I went into Power Options and set it to "go into sleep mode" after one minute. At that time, the screen went dark and fans shut down, and the noise went away. After I "woke up" the system and entered my password, all functions resumed along with the fans and the noise, all simultaneously.
If anyone would care to jump in here, I'd love to hear ideas on what is happening, especially with the noise issue. Obviously, I'm no techie.
Sounds like a fan throttling issue. Because the fans do slow down when in sleep state, most likely is a setting that they did not adjust when they replaced the mobo. It could be in BIOS, I am not familiar with the BIOS of that model.
Best thing would be to check with someone from Dell to see if there are some tweaking options that are not adjusted.