1 simple question: how is the noise of the Dell Dimension 8300?

The noise from the mid-tower case is very low, in my experience. Small Form Factor units are also very quiet. Dells in general are quieter than pretty much every mainstream PC offering. You would have to Do-It-Yourself a quiet solution to get better than the noise lefel of a Dell.

I got an 8300 almost free through my employer with a Radeon 9800 and a 2.6Ghz P4 w/800Mhz FSB. The fan on the Radeon 9800 is LOUD, it drowns out the noise of the harddisk and emits a high pitched whine. I replaced the Radeon fan with the Zalman passive heat sink last night which brought the noise level down considerably. Now the harddrive (Seagate Baracude IV 120GB) is too loud so I am going to look into ways to sound dampen it. The case has two fans, one for the power supply and another which vents air from outside the case to cool the CPU through a plastic duct. The fan which cools the CPU made by Sensflo (120mm?) emits a pitter-patter noise, so I'm looking into replacing it next. I also cut out the venting around the powersupply fan to provide better air flow. There is already a grill on the back of the 8300 case for the powersupply so the venting on the psu doesn't serve any usefull purpose.
In order to get this thing really silent I think I am going to need to replace both fans and dampen the hard disk and probably sound proof the case. I use the 8300 as part of a home theater rig to play movies, music, games etc, so ideally I would like it to be totally silent. After reading the guides on this site it sounds like that would be alot easier and cheaper to acheive by building the system yourself.

Barracuda IV 120GB? Most impressive!

I believe that the fan used on the 8300 series is a 92mm, but you never know...Dell could have changed the fan size from the 8250 series (basically P4 HT with Rambus 1066), but I highly doubt this.

Yeah, I guess it must have been custom made for Dell.

I have an 8300 as well, but I'm pretty sure, at least on mine, that the case fan is an exhaust fan. I say this because I feel air pressure when I hold my hand on the outside of the case, and because there is dust at the small vent holes on the front of the case under the smile-shaped panel (presumably intake ventilation).

You're saying yours is an intake fan?

Someone actually had a great idea to improve airflow over the hs:
http://forums.silentpcreview.com/viewto ... highlight=

Anyway...it's 92mm fan, the case/shroud fan, that is.

My 80mm psu fan started to get really noisy after a while (computer on 24x7) and the 92mm fan, too. Replaced psu fan w/Nexus 80 mm, but still was somewhat noisy at 12v, but okay at 5 volts. Maybe stock fan is okay at 5 v, too.

Taking out the grill vents at the back will probably help, but didn't do it for future prying-baby-fingers safety considerations.

Sux that I dunno how hot the temps are since dell's m/b don't to temp readings and now that I have 3 HDD.....along with 1CDROMand another 1 DVD drive.

Anyway, to answer your question, the 8300 can be quite noisy.
Although I heard that some people called dell to warranty-replace the case/shroud fan for something much more silent.