System RAM
This is not as much of an issue as it once was. Memory these days is very affordable, despite the current spike in prices. A couple of Gigabytes of DDR2 value ram was available for about PKR. 9000 beginning of last year. Now you can buy top of the line RAM, twice as much for less than the quoted price.
DDR2s days are numbered. Both AMD and Intel have moved their platforms to the next generation DDR3 RAM. Expect DDR2 to die a prolonged death.
If you are in for a new system and are eyeing a Core i7 “9” series processor make sure you buy your ram in sets of 3s rather than the usual two. The reason is that these processors have a triple channel memory controller. The real world benefits (read: gaming) are not significant, but there are application (especially synthetic benchmarks) that do take advantage of extra RAM bandwidth.
The other thing to keep in mind is that Intel’s new line up also need RAM with a voltage of 1.65V. This limitation will not apply to those who know how Core series processors operate. The limitation arises as Intel’s specs lay down that The memory Voltage should be with in .05 volts of Quick Path Interconnect (to RAM) voltage. As that is ~1.50 (at default) and keeping a certain safety margin, memory voltage that is acceptable is 1.65V. If you are into over-clocking at over volts, than this obviously can be circumvented by raising the QPI voltage.
These days it is pretty much possible to “cheaply” acquire 4 GB of DDR2 ram. Coupled with a 64bit Operating System (OS; to take advantage of the extra memory), it is pretty sufficient. If you are running a Core i7 “9” series processor, think of either 3 GB for a 32bit OS or 6 GB for a 64bit OS.
DDR3 is more expensive as compared to DDR2, but the difference is shrinking and probably will be wiped out during the next year when Intel will ramp up Core processor’s production and kill of Core2 series altogether.
The Power Supply
There is no such thing as a “free” lunch. That holds true for power supplies more than anything else. You can find 600 watt power supplies that are branded for about PKR. 5000. You can also find 600 watt power supplies that go for about twice as much. Both branded.
So why is one charging almost twice the amount. Are the simply banking on their name? Unfortunately no. There is more to power supplies than meets the eye.
There are several factors THAT must be considered before you decide to dish out your hard earned cash. As I said there is no such thing as a “free” lunch; you will see how the more expensive power supply is the ONLY option available.
Where are all the Watts coming from?
Modern computer systems rely on most of their power coming in from the +12V line. Power supplies provide power to your computer using two different power lines. +5V and +12V. Almost all the power to your graphics card is going to come from the +12V line. Most cheap, branded and high rated power supplies have more power on the +5V line. It has the requisite Watts but they are useless to you as they are coming in from the wrong line.
While we are on wattage; Your power supply will ONLY SUPPLY as much power as needed by the PC. A 600 Watt unit WILL NOT supply 600 watts continuously. It will only supply as much power as needed, even if it is only 10 watts (or even less).
+12V Lanes
Now that we know where the power needs to be coming from, we need to get it. There are two ways to get this power:
- Split Rail
- Single Rail (or split rails that behave as single rails)
1. Split Rail
This was more of a ATX design requirement that anything else. ATX spec laid down that the maximum amperage on +12V rail could only be 20 amps. Most manufacturers at the time used 18 amps. So how did they provide extra power? Simply by adding another rail. So you can have 2 rails that provide the requisite power. Need more? Add another rail!
Say you have a 600 Watt power supply. It has 400 Watts on +12V rails. Remember Power equals volts times amps:
Rail 1: 18amps x 12votls =~ 200 Watts
Rail 2: 18amps x 12volts =~ 200 Watts
Is there something wrong with split rails? Generally speaking no. They do have ONE big issue. Load balancing.
Suppose your GPU needs about 180 Watts, the rest of the system needs the same. What if u simply put all the load onto one rail?
To over come this, most split rail power supplies have instructions on how to load balance. A nuisance at least.
2. Single Rail (or split rails that behave as a single rail)
As the name suggests, you do not need to worry about load balancing here. The power supply either has a single rail or the rails behave as one. Definitely better
Power Conversion Factor (PFC)
We use 220Volts, Americans (and certain European nations) use 110 Volts. To select the input voltage power supplies either have passive PFC where input voltage has to be selected. Better power supplies can work over a range of voltages called Active PFC.
This is very much like the advertised refrigerators which say that they are immune to brown outs. They have active PFC.
This is a an over simplification, to get the point across.
80+ Silver & Gold Certification
This is the latest rating of power supplies. Power supplies like all machines have an efficiency rating. This simply mean how efficiently they can provide power to your PC.
As the load on power supplies increase, so does their efficiency. Peak efficiency is near maximal load. This certification requires 80% or more efficiency over a wider range of loads (80% efficiency for as loads as low as 20%). How does this affect you? Energy conservation. The better the efficiency, the less energy is lost as heat.
The certifications range from white (for 110V units only) to gold. Gold being the best. If you want to know more about this follow the link below.
80+ Rated Computer Power Supplies
All these features ("fat" +12V rail with ample power, single +12V rail, Active PFC, and usually silver or gold certification) is available on the more expensive unit. These features are not merely for show. They are very useful. Get a good power supply. You won't be sorry. Trust me.
Power supply is one computer component that I'd advise you to buy with as much foresight as possible. This is one component that you can go without upgrading for quiet a significant amount of time. If your current requirements stand at around 400 Watts, get a 600 Watt PC.
DO NOT USE online power supply calculation tools! They will always over calculate your power requirements. Rather look at on line reviews and figure out your needs from them.
Power Supply Recommendation
As for brands, there is only one company available locally that I can openly recommend: Corsair. Figure out how much you need, get a corsair. If you can find a silverstone, that will also do. But for me it is Corsair all the way. If you do decide to get your own favorite brand make sure it delivers enough power on the +12V line. These days upwards of 40 amps is some thing that everyone should gun for.
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