Power supply and UPS question

[r0bc]

Would it be OK to use a 1000w power supply with a 900w UPS?
I was thinking because it would never be under that much of a load I'd be safe but I'm not sure.
I have the UPS but I need to order a new PSU, I'd like to get the HX1000W but I can get the HX850 if its safer.

[3.0charlie]

There is no relation between a PSU and a UPS. The higher Watts and Volt-Amps only allow for a longer runtime at full load.

[MpG]

As long as you understand that a 1000 watt PSU can provide up to 1000W to the computer. Owing to inefficiencies in the conversion, that can require over 1200W from the wall, which obviously more than the UPS is rated to output. And while technically, the UPS will probably take it for a short period of time, UPS's also represent a sector full of companies looking for places to cut costs, especially if they can hide it from the average customer. And owing to the discharge characteristics of lead-acid batteries, the UPS's battery runtime under over-current conditions will be VERY short under the best of circumstances. So I'd be careful about exceeding the UPS's rated specs, just in case (the rig in your system specs is in no danger of doing that).

Having said all that, while the HX1000 is an excellent PSU, the HX850 is built on a newer and better platform, aside from being rated for a little lower wattage. And it'll still have no trouble powering even high-end SLI/XFire setups.

[MarkOne]

You can’t exceed the capacity in watts of your UPS, the overload protection will shut it down. It’s the kind of battery inside the UPS who make them run longer, not the rating of the UPS. A 500 watts UPS can have stronger battery . Than a cheap 900w one.
It’s not the size of the PSU who is important , it’s the total Amps draw by the system. 1000 w psu is the limits this PSU can output, not the quantity it use .

Originally Posted by 3.0charlie

There is no relation between a PSU and a UPS. The higher Watts and Volt-Amps only allow for a longer runtime at full load.

[3.0charlie]

This is not what the OP asked. He asked if he could use a 1Kw PSU on a 900W UPS - he did not mention any load.

Now, before we see a pull of 1kW from the wall, it will be a while...

[MarkOne]

3.0 , It's what I said.... he can use a 1000 w PSU with a 900 watts UPS, as long as the draw do not exceed 900 watts , he have to include also the monitor .

Originally Posted by MarkOne

........It’s not the size of the PSU who is important , it’s the total Amps draw by the system. 1000 w psu is the limits this PSU can output, not the quantity it use .

[Zero82z]

Originally Posted by 3.0charlie

This is not what the OP asked. He asked if he could use a 1Kw PSU on a 900W UPS - he did not mention any load.

Just because he asked the wrong question doesn't mean he shouldn't be given the right answer ;).

[r0bc]

I was using a 600w Opti UPS and the overload alarm keep sounding when the computer was under load so I ordered a Cyberpower 900w UPS last week and the day after I started using it the PSU took a crap. I partly think the UPS is faulty but maybe it was a coincidence. The retailer said they would replace both if it is the UPS but I'm half afraid if I order a 1000w and this one craps they won't cover it. Maybe it safer to order the HX850.

[Zero82z]

Originally Posted by r0bc

I was using a 600w Opti UPS and the overload alarm keep sounding when the computer was under load so I ordered a Cyberpower 900w UPS last week and the day after I started using it the PSU took a crap. I partly think the UPS is faulty but maybe it was a coincidence. The retailer said they would replace both if it is the UPS but I'm half afraid if I order a 1000w and this one craps they won't cover it. Maybe it safer to order the HX850.

As has already been explained, it's not the output capacity of the PSU that matters, it's the total power consumption of your system.

Let's say you have a system that draws 300W of power. Let's say that you have a 400W PSU and a 1000W PSU which are both 80% efficient at a 300W load, so both will be pulling 375W from the wall. You can use both PSUs with a 500W UPS even though one of them is 1000W, since the actual amount of power that your system pulls from the wall is still within the rating of your UPS. In the same vein, it doesn't matter if you get the HX850 or HX1000. Your system will still pull about the same amount of power from the wall, so you can use either one with a 900W UPS (providing your total wall draw is below 900W), even though the HX1000 is a 1000W PSU.

[r0bc]

Originally Posted by r0bc

I was thinking because it would never be under that much of a load I'd be safe but I'm not sure.

Thanks thats what I was thinking but wasn't sure .... ordered the HX1000