I've had my P180 since 2006 and it's been a great case. At its release there wasn't a better case for quiet computing but over time the lack of cable management, separate chamber for power supply, and heavy weight caused me to start looking for a replacement. As I currently use a mATX motherboard I naturally looked at the Temjin TJ08E and the Define Mini as possible replacements. The Define Mini appeared to be a safe choice but it was pretty large for an mATX case and I thought about experimenting with more positive pressure to keep dust out. The TJ08E is a better size but the feedback on the AP181 being too noisy here made me afraid to commit to buying one (I tried the PS07 but wasn't impressed with temps).
The Raven RV03 was available locally and I decided to give it a try to get a personal feel as to how the AP181 sounded and performed.
Intel Core i7 875K stock (95 watt TDP)
Scythe Mugen 2 with 2 Scythe 1200 Slipstreams at 5V
Sapphire Radeon 6850 with Accelero + Slipstream at 5V
Intel 330 SSD (No hard drives)
With these components housed in a P180 and placed under a desk the fans are inaudible. Any type of electric buzzing (monitor or coil whine) can be heard clearly late at night.
I took temperature readings with the P180 using a single 1200rpm Slipstream at 5V. The Raven RV03 was tested with the dual AP181 on the bottom running at 5V and the fan controller setting on High (The fans don't start on Low at 5V) and the top exhaust off.
Here are the results:
CPU 1 37 31
CPU 2 34 26
CPU 3 36 27
CPU 4 33 27
GPU 44 38
Prime only (10 minutes, 8 workers)
CPU 1 76 61
CPU 2 78 61
CPU 3 72 58
CPU 4 76 61
GPU 46 38
Furmark only (10 minutes)
CPU 1 61 46
CPU 2 49 32
CPU 3 51 36
CPU 4 47 32
GPU 69 60
Furmark + Prime only (5 minutes, 4 workers)
CPU 1 78 60
CPU 2 78 56
CPU 3 72 55
CPU 4 76 54
GPU 70 61
Sorry about the formatting above. Note that the Prime + Furmark combined test was done with only 4 worker threads because I wasn't sure if the P180 configuration could handle with 8 worker threads.
The temp differences were pretty significant especially for the CPU with about a 15C degrees difference. GPU ended up being about 10C cooler.
From a noise perspective the AP181s are clearly audible and unsurprisingly the loudest thing in the system. I ran them at 5V on High and unfortunately SPCR did not test the fans at this configuration so I am not sure what the db rating is. I don't have two Zalman fanmates or a sophisticated fan controller with voltage readings so I can't get precise 9V to emulate the SPCR voltages for testing.
Tonally the fans aren't completely smooth but they don't sound terrible. Due to the size and the location of the fans it is a rather low frequency droning in the background that is not as annoying as a higher pitched smaller fan at the same db rating. I think noise can be further reduced by running the fans at 9V on Low compared to 5V on High and it would still produce acceptable temperatures. The case itself is pretty nicely laid out but putting a single video card, mATX board, and SSD feels a bit silly in a ~70L case.
With this experience I am definitely leaning away from the TJ08 because the front placement as opposed to the bottom placement of the AP181 would add an additional 1-2 db. It also reinforced my belief that a positive pressure quiet airflow setup is very difficult to do as the slow speed fans don't move enough air. The single exhaust at the rear of the case is probably the best placement when using low airflow fans.
Another thing to note is that "silent" is not always better than "quiet". Even if your fans are inaudible there will be other sources of electrical noise like buzzing monitors, power adapters, power supplies and other forms of coil whine. These are usually not smooth sounding and can sometimes be more disruptive and annoying than a smoother sounding (but louder) fan.