One of the main components of any desktop system, and the one most ignored, is the power supply (SMPS).
95% of India-assembled systems use cheap no-name China SMPS's. Most large reseller "brands" also sell these cheapo power supplies.
The reason for their popularity is the compelling price difference. A "no-name" / "reseller brand" power supply retails for as low as Rs 500 for 450 watts (example), while the good brands start at Rs 2,000+ for 350w. So, it seems as though not only are you getting a cheaper power supply, you are getting more power in the bargain.
As usual, the devil is in the (technical) details. However, let's start by seeing something even a layman can understand:
Catch 2:
The bulk requirement for power in most computers comes from the 12v rail. However, components that supply reliable 12v generate heat. This must be removed by using quality heatsinks and fans. The "no-name" SMPS reduces the amperage on 12v so that it can skimp on the (heavy) heatsink. However, to maintain a 450w rating, it raises the current available (amperage) on 5v to absurd levels.
This becomes clearer when we compare with other "real" power supplies as well:
In every case, we see that 3.3v+5v power (wattage) in "no-name" is absurdly high when compared to the expensive "real" power supplies. Similarly, the 12v is very low.
On the "no-name", there is no way one can actually reach the absurdly high load provisioned on 3.3v+5v. However, you will definitely max out the 12v power available even with a very ordinary load.
Catch 3:
No power supply, no matter how good, can work with 100% efficiency. In every case for the real power supplies, the theoretical rating (wattage of 3.3v+5v+12v) is far over the actual rating. However, in the "no-name", the theoretical rating is treated as the actual rating, with no mention of power conversion efficiency.
Note the massive difference in Antec: This doesn't mean that it is inefficient, it just means that as load increases in 12v1, the max load on 12v2, 3.3v and 5v will reduce, and vice-versa. In other words, there is no way Antec expects you to touch the theoretical load on all rails (3.3v, 5v, 12v1, 12v2) simultaneously.
These "no-name" cheap and unreliable power supplies are the leading cause for failure in most systems. Unfortunately, while the power supplies themselves rarely fail, they invariably cause damage to sensitive electronics such as the motherboard, hard disk, etc, due to non-spec or unreliable supply of load.
A good power supply not only provides reliable and stable power, it will usually sacrifice itself (by failing) when non-spec power (eg over-current) is supplied, to protect sensitive (and usually expensive) components.
So the next time you find your Graphic card, HDD or DVD drive acting up, take a good, hard look at the power supply.
Spend a little more on your power supply, it will reward you in the long run with reliable system performance.
If you are buying an assembled system, insist on a good power supply, and compare the wattage chart with those mentioned above. Remember, 12V load is important, the others less so.
95% of India-assembled systems use cheap no-name China SMPS's. Most large reseller "brands" also sell these cheapo power supplies.
The reason for their popularity is the compelling price difference. A "no-name" / "reseller brand" power supply retails for as low as Rs 500 for 450 watts (example), while the good brands start at Rs 2,000+ for 350w. So, it seems as though not only are you getting a cheaper power supply, you are getting more power in the bargain.
As usual, the devil is in the (technical) details. However, let's start by seeing something even a layman can understand:
 |  |
"no-name" SMPS 450w
Weight : 584.6 gms |
Antec VP450P 450w
Weight: 1618.1 gms |
The Antec SMPS on the right weighs almost 3 times (~ 276%) more than the "no-name" SMPS on the left.
However, this is only a symptom; the real problem? Read on...
Both power supplies claim to have 450w output. Background info: SMPS's output at different voltages, as shown below:
 |  |
3.3v x 25A = 82.5 w
5v x 38A = 190 w 12v x 15A = 180 w Theoretical Total : 452.5 (~ 450w) Efficiency not mentioned: unknown |
3.3v x 24A = 79.2 w
5v x 15A = 75 w 12v (1,2) x 18A (each) = 432 w Theoretical total: 586 w Efficiency mentioned 78% Total: 457.08 (~ 450 w) |
Catch 1:
The total wattage calculation is arrived by multiplying the output voltage with it's corresponding amperage rating. So in this case, both supply power output over 450 w. However, note that the Antec actually can supply a maximum theoretical output of over 580w - but not reliably. Given a mentioned efficiency of 78%, it can reliably supply a continuous load of 450 w. There is no efficiency ratio mentioned in the case of "no-name", however, it definitely cannot be 100%.
Catch 2:
The bulk requirement for power in most computers comes from the 12v rail. However, components that supply reliable 12v generate heat. This must be removed by using quality heatsinks and fans. The "no-name" SMPS reduces the amperage on 12v so that it can skimp on the (heavy) heatsink. However, to maintain a 450w rating, it raises the current available (amperage) on 5v to absurd levels.
This becomes clearer when we compare with other "real" power supplies as well:
Brand / Model
|
3.3v
|
5v
|
12v
|
3.3v+5v
|
12v
|
"no-name" 450w
|
25 A
|
38 A
|
15 A
|
272w
|
180w
|
Cooler Master CM350 350w
|
20 A
|
12A
|
10 A + 13 A
|
126w
|
276w
|
Antec VP450P 450w
|
24 A
|
15 A
|
18 A + 18 A
|
154w
|
432w
|
Circle Tech CT 500w
|
20 A
|
20 A
|
32 A
|
166w
|
384w
|
In every case, we see that 3.3v+5v power (wattage) in "no-name" is absurdly high when compared to the expensive "real" power supplies. Similarly, the 12v is very low.
On the "no-name", there is no way one can actually reach the absurdly high load provisioned on 3.3v+5v. However, you will definitely max out the 12v power available even with a very ordinary load.
Catch 3:
Brand / Model
|
Calculated rating
(theoretical) |
Actual rating
mentioned |
"no-name" 450w
|
452.5w
|
450w
|
Cooler Master CM350 350w
|
402w
|
350w
|
Antec VP450P 450w
|
586.2w
|
450w
|
Circle Tech CT 500w
|
550w
|
500w
|
No power supply, no matter how good, can work with 100% efficiency. In every case for the real power supplies, the theoretical rating (wattage of 3.3v+5v+12v) is far over the actual rating. However, in the "no-name", the theoretical rating is treated as the actual rating, with no mention of power conversion efficiency.
Note the massive difference in Antec: This doesn't mean that it is inefficient, it just means that as load increases in 12v1, the max load on 12v2, 3.3v and 5v will reduce, and vice-versa. In other words, there is no way Antec expects you to touch the theoretical load on all rails (3.3v, 5v, 12v1, 12v2) simultaneously.
These "no-name" cheap and unreliable power supplies are the leading cause for failure in most systems. Unfortunately, while the power supplies themselves rarely fail, they invariably cause damage to sensitive electronics such as the motherboard, hard disk, etc, due to non-spec or unreliable supply of load.
A good power supply not only provides reliable and stable power, it will usually sacrifice itself (by failing) when non-spec power (eg over-current) is supplied, to protect sensitive (and usually expensive) components.
So the next time you find your Graphic card, HDD or DVD drive acting up, take a good, hard look at the power supply.
Spend a little more on your power supply, it will reward you in the long run with reliable system performance.
If you are buying an assembled system, insist on a good power supply, and compare the wattage chart with those mentioned above. Remember, 12V load is important, the others less so.
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