Fluffy said:
will it improve performance
Understand a PSU does not really affect "performance" in terms of speed so if you looking to improve your game play, for example, a new PSU will not make your computer run better. If your current PSU is failing, or underrated, it can affect "stability" of the system which typically appears as sudden reboots, or system freezes, or sometimes, corrupt graphics (pixelization). If that's not an issue, a new PSU will not help or allow you to download files faster, or surf the net faster.
bobkn said:
I have a pathological fondness for PSUs with single 12V rails. A few years ago, some multiple-rail PSUs did badly with high-powered graphics cards, because of a poor power distribution design. That probably no longer applies to reputable makers.
I'm with Bob on this but it can still be an issue. The idea behind multiple rails (rails "basically" being independent and isolated voltages supplied by the PSU) is to ensure there would always be adequate power on each rail for the various devices being powered by the PSU - so the HDs would not hog all the power from the graphics card, for example.
As bobkn noted, cheap supplies did (and do) a poor job of managing the distribution, but even quality multi-rail supplies, then and now, have an inherent deficiency: they must always reserve some power for each rail, even if not, or under used. This means you may need to buy a higher rated multi-rail PSU to ensure any single rail has enough horsepower available to meet demands.
In terms of "theory", the need for that reserve is NOT a quality issue, but it can affect your budget. Another issue affecting budget is simply the complexity of building a multi-rail PSU over single rail PSU. Common sense tells us a more complex design costs more to design and build. It also means it introduces more possibilities for something to go wrong - even when the highest quality parts and manufacturing techniques are used.
It is also important to note a computer will draw from the wall outlet what it needs, and NOT what the PSU is rated for. So if the computer needs 300 watts, it will draw from the wall 300 watts (plus some for PSU overhead and inefficiencies) regardless if the PSU is a 400 watt supply or a 1000 watt supply.
ignatzatsonic said:
You can go to any of the multitude of online sites that will evaluate your wattage requirements. The problems with those sites is that they invariably over-estimate the wattage because they assume the user will go out and buy a mediocre quality PSU rated at 600 that can supply only 400 quality watts. Better to buy a reliable unit that can supply a quality 400.
I agree 100%. Too often you will see monster supplies recommended when not needed. That said, if your computer needs 300 watts, getting a 300 watt supply would not be a good idea because that PSU will be maxed out the full time. It will have no room left for future expansion or upgrades, and, it likely will be running very warm all the time causing it's fan to run full speed (read: loud!) full time too. Where a decent 450W supply will let you add a couple sticks of RAM without worries, and the fan (if speed controlled) may be able to slow down to keep noise levels at bay.
I agree that modular connections are nice for tidiness, and air flow in the case too. But like everything else, there are cheap connectors and quality connectors - but even the best can fail, and all add some resistance to the circuit, plus an opportunity for dust and dirt to get in the way.
So, below is my canned text on sizing and choosing a new PSU. I like the eXtreme PSU Calculator because it does NOT recommend monster drives. In fact, many fear it recommends too small of PSUs. It does not - it just seems that way because we have been led to believe (brainwashed?) that bigger is better. It recommends the minimum. It (using the default settings) does not account for aging or future upgrades so I have suggested possible setting changes to compensate to help ensure you get a PSU that will carry you through years of reliable service.
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Use the
eXtreme PSU Calculator Lite to determine your power supply unit (PSU) requirements. Plug in all the hardware you think you might have in 2 or 3 years (extra drives, bigger or 2nd video card, more RAM, etc.). Be sure to read and heed the notes at the bottom of the page. I recommend setting Capacitor Aging to 30%, and if you participate in distributive computing projects (e.g. BOINC or Folding@Home), I recommend setting TDP to 100%. These steps ensure the supply has adequate head room for stress free operation and future demands. Research your video card and pay particular attention to the power supply requirements for your card listed on your video card maker's website. If not listed, check a comparable card (same graphics engine and RAM) from a different maker. The key specifications, in order of importance are:
- Current (amperage or amps) on the +12V rail,
- Efficiency,
- Total wattage.
Then look for power supply brands listed under the "Good" column of
PC Mechanic's PSU Reference List. Ensure the supplied amperage on the +12V rails of your chosen PSU meets the requirements of your video card. Don't try to save a few dollars by getting a cheap supply. And don't count on supplies that come included with a case. They are often underrated, budget or poor quality models "tossed in" to make the case sale. Digital electronics, including CPUs, RAM, and today's advanced graphics cards, need clean, stable power. A good, well chosen supply will provide years of service and upgrade wiggle room. I strongly recommend you pick a supply with an efficiency rating equal to, or greater than 80%. Look for the
80 Plus - EnergyStar Compliant label. And don't forget to budget for a good UPS with AVR (automatic voltage regulation), as surge and spike protectors are inadequate.
