Power supply units are rated based on their output and efficiency. When more equipment is connected, a higher output power supply is needed.
Watts.
You need to make sure you buy a power supply that is rated for your motherboard. Common ratings are 350w, 400w and 500w.
UPS = Uninterruptible Power Supply
You can't. Buy the correct power supply.
To operate at its rated power, a lamp must be subject to its rated voltage (the supply voltage). As each branch of a parallel circuit is subject to the same voltage (the supply voltage), each lamp will operate at its rated power.
A dual power supply refers to a system that provides two separate power sources to a device or circuit. This setup offers redundancy and can help improve reliability in case one power source fails. It is commonly used in critical systems where uninterrupted power supply is necessary.
The 2wire 2700 and 2701 models both use a 5.1 volt power supply rated 2 or 2.2 amps
Generally you want to increase the capacity of the power supply (rated in watts) if you want to add more components to the computer which require substantial amounts of power, such as graphics cards. You may also in some circumstances find that the computer has an under-specified power supply installed when it is sold/built and so it will need to be upgraded just to be able to power the existing components.An under-rated power supply will manifest itself through system instability (randomly resetting or turning off when you do something that places a load on the system).
When a power supply is overloaded, it can overheat and potentially fail. This can lead to damage to the connected devices, such as a short circuit or a power surge, which can result in data loss or hardware damage. It is important to ensure that the power supply is rated to handle the load requirements of all connected devices to prevent overloading.
Your question is confusing, but if you are asking whether you can use a 9V/250 mA adapter to supply a load device rated at 5 V/1000 mA, then the rule is quite straightforward. The adapter's rated output voltage must match that of the intended load, but its rated current must exceed that of the load. So in your example, you cannot use the adapter with the intended load.
That would be a "surge protector". Note that many UPS (uninterruptable power supply) units include this functionality too.
A redundant power supply is two or more units in one package, where each can supply the full amount of power to the system, such that if one fails, the other will take over and the system never goes down. In most modern redundant power supplies, the dead one can be replaced while the system is still running, called hot-swapping.