For what its worth, a short while back, my main PC was an NF7S & XPM @ 2.7. I used 4xDelta 80mm Front + 2 x Delta Rear, plus a Delta on an SK700 ( Or SLK7? - the one that takes the 80mm cos I have a few that do, a few that dont, so dont know which one is which these days ? )
Anyway, my temps were hovering at 48c idle and shooting up to 60+ under load.
I then fancied a large case, and was undecided as to the Coolermaster Stacker, or the Thermaltake armour, so I thought stuff it, I will get both.
The CMS I found a little overhyped actually and opted to use the TTA as my main box and use the CMS in the attic... Plus the kids dont touch my attic PC I s'pose!?
Anyway, my temps dropped to 22c instantly... The most obvious part of this was being in a new case, I also removed all the dust from the components so that made a massive help, but the drop also allowed me to adjust my cooling options... I lost the Deltas from the case, and the CPU cooler I opted for a much quieter YSTech and my PC was now near silent.
I have since upped the PC to A64 and I too use an artic 64 in that case, and the PC is now 100% silent. I am not using the top 92mm fan in the case, but I am using the one at the back as I have my 2 SATA drives there, and the front 120mm is blowing across a further 3 HDs, so with 5 Hard Drives, and 4 DVDRW Drives, even when its burning 4 disks at a time, as well as defragging a couple of my HDs, the whoel system never makes a single sound except for when its accessing the raptor, and even then, its a very quiet purr.
This has taught me one massive lesson, and that is the case is a far more important part of the PC than I originally put it down as.
Since then, with all my PCs ( And I have a silly ammount of the buggers ) I have made sure that the Case is up to scratch, and if not, then it gets assigned to a lesser job, or to the bin.
The only exception I have at this time, is my 8 year old sons PC and thats only because I have let im have my SCSI Drives and I doubt that a couple of screamers are going to make much difference judging by the noise the drives make... They are so loud that the Deltas sound gets drowned out by the drives grinding away, and thats sad, but hey, you dont give a stuff about a silyy little bit of wind when you have me and my kids all killing each other at UT do you? LOL
Anyway, I have lost it now.
Noises to look for?
PSU & FAN
Case Fans
GFX / NB Fans - the little ones whine and catch dust quicker than bigger ones
Make sure that everything is screwed down, drives are well seated, Motherboard and cables are held down well, and tidy etc
Cables in a case can often cause the wind from fans to blow in various ways, this can, if oyu use powerful fans, made a sound, although I have not had any know issue like that myself.
A great solution to rattles is blue-tack, or even card. At times when I have hardware rattles, I sometimes use insulating tape too, all with the idea of cuhioning things like Drives and Fans, and I have even used insulating tape over the holes in a Mobo, and pushed the holes through as this can help avoid shorting, plus its useful for when I cant be bothered to use washers, but then again, I cant think of a time when I ever used them?
End of the day, 95% of noise is the fans, so always check each and every fan.
Also another thing to look into, is the grills on the case for the fans... Consider cutting the grills out completely and use a standard fan grill ( the ones like a spiders web - you know the ones I mean ) and fan grills can cause a lot of noise in some cases.
There, that should get you going, if not, then it will put you to sleep for sure!