Kedu sanoi:
Jahas, täältäkin löytyy jo xbox 360 + pari peliä ja pakko vähän kommentoida. Laite on mielestäni pelikäytössä todella äänekäs (lue: äänekkäämpi kuin eka xbox), hurisee kaiken aikaa varsin miehekkäästi (prossun jäähdytys ?). Dvd-leffaa katsottaessa taas huomattavasti hiljaisempi kuin alkup. xbox. Ainoassa testaamassani leffassa kuva hypähteli pikku nypäyksin kaiken aikaa ja kuva/ääni synkka oli pielessä (,tämä saattaa hyvinkin johtua siitä, että kuva kiertää halppisdigiboxini kautta töllöön komposiittina). Pitää tutkia asiaa syvemmälti.
Siinä on käytetty jäähdytykseen eräänlaista "vesijäähdytystä" ja sen lisäksi on kaksi tuuletinta, joiden pyörintänopeus säätyy sen mukaan paljonko jäähdytystä tarvitaan. Eli raskas peli vaatii koneelta enemmän, jolloin tuulettimet pyörivät kovaa, kun taas DVD:n toistossa lämpöä syntyy paljon vähemmän ja tuulettimet pyörivät paljon pienemmillä kierroksilla.
Tässä on XBOX.com sivulta lainattua juttua asiasta: (Tuo JR on Jeff Reents, XBOX360:sen Lead Mechanical Engineer)
Xbox.com: What are the constraints of packing that power in a smaller case?
JR: Heat, for one. All that power generates a lot of heat, and you have to find a way to keep the unit cool. Fan size was interesting. We originally wanted to put in a single 80mm fan. But we couldn't fit it in the final form factor chassis.
We couldn't just go with one 60mm fan because it would not provide the required cooling—as the diameter of the fan increases the air flow performance per revolution increases exponentially. So we ended up putting in two 60mm fans, and we came up with a water-cooled heat sink as well for the CPU. We've actually applied for a patent on that one.
The water cooled term is being used loosely; actually it is a heat sink constructed of a copper base, aluminum stamped fins and copper heat pipe. The heat pipe contains water and a vacuum is pulled on the pipe prior to sealing.
Water under a vacuum boils at a lower temperature than at atmospheric pressure, so when the water boils and becomes steam, the steam rises and moves the heat higher into the fins where the air flow from the fans can extract the heat more efficiently. Once the steam is cooled it condenses and flows back down the pipe as water to the copper base of the heat sink, which is attached to the processor to continue the condensing and cooling processes cycle.
Xbox.com: Won't two fans make an awful racket while I'm trying to play games or chat or watch a movie?
JR: Actually, we tried to balance the console form factor, thermal performance, acoustic performance and cost of components. With the form factor and system power a fixed specification (determining the minimum airflow requirement and fan size) we use thermal sensing diodes in the main ICs (GPU and CPU) and thermal algorithm firmware that reads the diode temperatures and adjust the fan RPMs by altering the fan voltage to a predetermined minimum requirement that minimizes the fan speed (minimizes the acoustics) while providing the required cooling capacity for the system.
The required cooling capacity of the fans is determined by the system electronics usage scenario; high cooling capacity is needed for intense game play applications, and less cooling capacity is needed for DVD movie viewing. Plus there's the operating environment (ambient temperature and altitude of the console) to consider.