|The power supply must have enough +5vSB amperage capacity to handle what the mboard requires in order for Standby or Hibernate to work properly. That should be at least what it was on the label for the original power supply. When you use an older used PS, that may be inadequate - it may work for a while, but if that's not actually adequate, eventually it won't. |
Brand name systems use el-cheapo power supplies.
In some cases Compaq and HP desktop systems use a BESTEC power supply model. BESTEC power supplies have a well known reputation of being a LOT more likely to malfunction than average, and if they fail completely, they are a LOT more likely to damage something else while failing, often the mboard.
If the main chipset drivers have not been installed, Windows may not have the proper information about how your particular mboard supports ACPI features (Standby, Hibernate, etc.). Sometimes Restart also doesn't work properly if they haven't been installed .
Whenever you load Windows from a regular Windows CD (or DVD) from scratch, after Setup is finished you must load the drivers for the mboard, particularly the main chipset drivers, in order for Windows to have the proper drivers for and information about your mboard hardware, including it's AGP or PCI-E, ACPI, USB 2.0 if it has it, and hard drive controller support. If you have a generic system and have the CD that came with the mboard, all the necessary drivers are on it. If you load drivers from the web, brand name system builders and mboard makers often DO NOT have the main chipset drivers listed in the downloads for your model - in that case you must go to the maker of the main chipset's web site, get the drivers, and load them.
You don't need to use Standby or Hibernate at all.
If you simply go to Control Panel - Power and set the hard drive to shut off the hard drive after xx minutes as Grasshopper has suggested, the hard drive will stop spinning after that time of inactivity by the user. If the monitor is not set to shut off before that time, you still have video, you're running the computer entirely from the ram, and if you then do something that requires hard drive access, the hard drive will spin up again, there being only a short delay for it to do so.
If you also set the monitor to shut off after XX minutes there, the screen will go black after that many minutes of inactivity from the user, but when you press a key or move a mouse, the monitor display will come back on again, the hard drive will spin up if it has been shut off.
If Standby won't work properly, set it to NEVER come on there.
NOTE that that, too, may not work properly if the main chipset drivers have not been loaded.
If you have added a graphics card in a slot the system did not have when you got the computer, the power supply must have enough capacity (wattage output, +12v output) to handle it being on the system.
Your power supply must have at least the minimum capacity required to support a system with the graphics card you are using installed, or the max graphics card you might install in the future.
(Onboard video - video built into the mboard - IS NOT A CARD ! )
If that info is not in the ad for the video card, you can go to the video card maker's web site and look up the specs for the model - often under system requirements - the minimum PS wattage, and, more important, the minimum amperage the PS must supply at 12v is stated. If you don't find that, any card with the same video chipset including any letters after the model number has very similar minimum PS requirements. Some power supplies have two or more +12v ratings - in that case, add those ratings to determine the total +12v current capacity.
If you're a gamer...
In most if not all cases, the max capacity rating of the PS is an intermittent rating. It's recommended that you do not load your PS to any more that 80% of that rating if you are going to be using something that puts a constant load on it, such as playing a recent game for hours on end. In that case, you multiply the min capacity stated for the system with the particular video chipset on the card by 1.25 to find the min. capacity of the PS you should get.