QUOTE (Janice Wei Lan @ Jun 23 2008, 01:22 AM)

....buat apa susah2?

diorang bukan nak repair tapi nak duit...nak sedikit upah ......
hmm, ni la silap tech, tau nak duit je, ade ilmu taknak kongsi taknak guna. rosak je trus tuka baru tanpa fikir dulu ape masalah n cari solution utk setiap masalah. contoh terdekat kat bawah ni la
QUOTE (Janice Wei Lan @ Jun 23 2008, 01:22 AM)

mcam aku pun kalau bende tuh tak menguntungkan aku dan merugikan msa aku mesti aku `halau` bende tuh keluar...
kepada tech2 komp, fikir balik ape motif korang buka kedai tu ya... kepada pengguna yg noob cam akuk, sebaiknya kite tak perlu support org2 yg sifat n sikapnya yg cenggini..
disini akuk sertakan beberapa sebab kenapa ramai user yang nak sgt pakai PSU2 yg power tu
Active PFCThe AC electric mains can be considered as having two types of power: active and reactive. Reactive power is generated in two cases: when the load current and the mains voltage are out of phase (that is, the load is inductive or capacitive) or when the load is non-linear. The PC power supply is a pronounced example of the second case. It will normally consume the mains current in short high impulses that coincide with the maximums of the mains voltage.
The problem is that while active power is fully transformed into useful work in the load, reactive power is not consumed at all. It is driven back into the mains. It is kind of wandering to and fro between the generator and the load, but it heats up the connecting wires as well as active power does. That's why reactive power must be got rid of.
The circuit called active PFC is the most efficient way to suppress reactive power. It is in fact an impulse transformer that is designed in such a way that its instantaneous consumed power is directly proportional to the instantaneous voltage in the mains. In other words, it is made linear on purpose and thus consumes active power only. The voltage from the output of the active PFC device goes right to the switching transformer of the power supply which used to be a reactive load due to its non-linearity. But now that it receives direct voltage, the non-linearity of the second transformer doesn't matter anymore because it is detached from the electric mains and cannot affect it.
The power factor is the measure of reactive power. It is the ratio of active power to the total of active and reactive power. It is about 0.65 with an ordinary PSU, but PSUs with active PFC have a power factor of 0.97-0.99. So, the active PFC device reduces reactive power almost to zero.
Power supply companies rather than the users that profit from active PFC because it reduces the computer's load on the electric mains by over one third. And this amounts to big numbers today when there is a PC standing on every office desk. From an ordinary user's point of view, active PFC makes no difference even when it comes to electricity bills. Home electricity supply meters measure only active power as yet. The manufacturers' claims that active PFC can in any way help your computer are nothing but marketing noise.
Active PFC is not an obligatory feature right now, but from the next year a power supply will have to have a power factor that can only be achieved with active PFC to pass the Energy Star certification (which is voluntary, though).
Passive PFCPassive PFC is the simplest way to correct the power factor. It is a small choke connected in series with the power supply. Its inductance is smoothing out the pulsation of the current consumed by the PSU and is thus reducing the level of non-linearity. There is a very small effect from passive PFC - the power factor grows only from 0.65 to 0.7-0.75. But while implementing active PFC requires a deep redesign of the PSU's high-voltage circuitry, passive PFC can be easily added into any existing power supply.
Power supplies with passive PFC with eventually be replaced with active-PFC models.
High efficiencyEfficiency is the ratio of input power to output power. The higher the efficiency of a PSU is, the less heat it generates and the quieter its cooling can be made. Your electricity bills will be lower if the efficiency is high, too.
The current version of the ATX12V 2.2 standard limits the PSU efficiency from below: a minimum of 72% at typical load, 70% at full load and 65% at low load. Besides that, there are optional numbers (an efficiency of 80% at nominal load) and the voluntary certification program "80 Plus" which requires that the PSU has an efficiency of 80% and higher at loads from 20% to maximum. The new Energy Star certification program to come to effect in 2007 will have the same requirements as in the 80 Plus.
Minimum Efficiency RequiredMinimum measured efficiency is required to be 70% at full and 72% at typical (~50%) load and 65% at light (~20%) load. The recommended guidance is 77% at full load, 80% at typical (50%) load and 75% at light (20%) load to provide direction for future requirements.
HIGH EFFICIENCY = LOWER HEAT = LOWER FAN SPEED = LOW NOICE
Low noiseThis means that the speed of the PSU fan is varied depending on temperature or, less often, on load power. This speed management is currently implemented in all PSUs, even cheapest ones, so the question is about the quality of implementation. This quality can be viewed from three aspects: the quality of the employed fan, the minimum speed of the fan, and the speed adjustment range. For example, simplest power supplies may have speed management, but the speed is changed from 2500rpm at a 50W load to 2700rpm at a 350W load. It's like the speed doesn't change at all.
Respectable manufacturers implement the fan speed management system properly, but often play another marketing trick. The fan speed (or the noise level) they write into the power supply specs is measured at a temperature of 18�C as reported by a sensor inside the PSU. This thermal sensor is usually installed somewhere in the hottest part of the PSU, on the heatsink with diode packs, so you can only have that temperature in reality if you put your PSU in a refrigerator. Although no one keeps PSUs in a fridge, the specification still contains an unrealistically pretty number like a noise level of 16dBA (this is quieter than the background noise in a quiet room). In reality, the room temperature is usually within 20-25�C, and the temperature inside the PC case is closer to 30�C. Of course, you can't get 16dBA under such conditions.
Source : Lowyat.Net Forum