thanks guys. I'll pick up a quiet 650w, with a good brand. cheers, Jay BTW, its amazing how affordable they are. you'd think PC builders would just do a little overkill so people didn't have to deal with this.
Not my business of course to tell you how to run yours.. but in all my years of trading, I've only had 2 power outages while I had positions on which induced me to call the broker and flatten until my power was restored. Rather than running a UPS all the time, suggest you just keep a cheap cell phone service handy instead... you don't even need that if you have a land line phone.... they run on central office battery.
Choosing the right PSU is NOT as simple as looking at a total wattage number. That is being far too simplistic. You need to do a little more homework and take a look at how strong the +12V rail is of the PSU, along with the +5.0V rail and +3.3V rail. Each of these rails supplies power to the various components of your computer. Wattage = Voltage x Amps If you see that a +12V rail line supplies 18A, that means that that voltage rail can supply a maximum of 216 watts of power. The reason why the +12V rail is so important is because it supplies power to the most demanding components of your computer system . . . including the processor, drives, cooling fans, AND graphics cards. I've seen measly 250W Dell PSU's totally blow away 400W PSU's by aftermarket companies because the +12V rail in the 400W PSU was a "joke" compared to the very robust +12V rail of the Dell. Again, you need to do a little more homework about the +12V rail because merely looking at TOTAL WATTAGE is far too simplistic! - - - - - - - - - - - - - NOTE: I have had a PC Power & Cooling Silencer 410W PSU in a backup Dell Dimension 8300 mini-tower for the past 5 years and it has done a fantastic job. Paid nearly $150 for it, and nowadays you can get it for as little as $60.00 at NewEgg.Com Comes with a very robust 23 Amp +12V rail too!
Hi Landis, Thanks for the explanation. When I look at the site of apc, I notice that there is a 1.6 factor difference between Watts and VA, see for example (drop down menu in the table): http://www.apc.com/products/family/index.cfm?id=251 isn't that something that needs to be taken into account? I realize that buying a more powerful PSU isn't a major issue in terms of cost, but a UPS with a factor 1.6 capacity difference is effecting the price (and I do need one). Thanks
Power can be measured differently, depending on the type of supply. Generally speaking, stick to using the Watt variable, when looking at supplies, rather than VA (the larger VA numbers look good for marketing purposes). Watts is often about 60% of direct VA. And although they sometimes measure the source power using different metrics, the loads (that you add up) will have equivalent wattage and VA values. So, if you add up the wattage requirements for loads (even using voltsXamps/load, as landis suggests) that is the amount of wattage required from the power source. If your monitors, video card, etc... require 500W, you should be good with 550-650W UPS (which depending on supply type, may be 650VA or 1,080VA). Also, as I mentioned earlier, and Landis mentioned, the usual load monster is the video card, so for your supply make sure you have the appropriate current/voltage molex outputs to drive your video card. Here's a little supply calculator to give you a feel of how to add up the loads. (have to check specific devices for specific V*A/load relationship, but Watts are given here). http://www.journeysystems.com/?power_supply_calculator Doesn't include calculations for monitors on UPS though.
Thanks for the help dtrader, I understand it now; once you know how this works, it's not that difficult.