PSU and UPS - how are they related ?

[virajk]

Ok so im putting up a new system with an existing GTX 460 & Rosewill Stallion 500W PSU. The UPS I have is rated at 360 Watts/6A and the last time I used it with an old system with the same GPU|PSU (6 months back to be precise) the ups was continuously beeping and abruptly dying out (ON load while Gaming - when every component is maxed out) so I had to underclock my GPU to stop that .

The UPS had problems and was repaired recently but with no computer system to test on.

Now with the new system coming up Im worried will the problem recur ?? Will it be able to handle to power requirements or is it not fit to do so.So how exactly does one decide the rating of the required UPS knowing the Power consumed by the Computer system as a whole ??

Technical insight at a fundamental level will be very helpful.

 

[Z1NONLY]

A PSU that produces 500w with an 80% efficiency rating will draw 625w from the outlet it's pugged into. (at max power)

Your UPS (battery-back up side) is that outlet, and it needs to be to provide that 625w in addition to the power drawn by all the other stuff that's plugged into the battery back-up outlets. (and I would leave myself some headroom too)

 

[virajk]

A PSU that produces 500w with an 80% efficiency rating will draw 625w from the outlet it's pugged into. (at max power)

Your UPS (battery-back up side) is that outlet, and it needs to be to provide that 625w in addition to the power drawn by all the other stuff that's plugged into the battery back-up outlets. (and I would leave myself some headroom too)

I read an article once on Tomshardware clearing the doubts on PSU efficiency, correct me if I am wrong -

PSU efficiency = (Power required,supplied to the system)/(Power that is actually drawn from the socket - in this case the UPS)

So it means that the UPS Power rating should always be greater than that of the PSU as no PSU will have an eff of 100% (assuming the powerdraw from the computer is the same as max rating of the PSU) .

 

[FinneousPJ]

Yes, that is the definition of efficiency.

 

[CaedenV]

I would not use Rosewill brand for anything that runs electricity through it. They make OK cases, but their electronics are typically really really bad. Please save yourself some trouble and get a better PSU if you have not already ordered it.

80% efficiency means that at peak efficiency you are loosing ~20% of power to heat, and that at lower and higher loads you are loosing more along the lines of ~30% of power to heat.

What you want to do is use a power calculator (there are tons of websites with really good ones), put in all your parts, and then add 20-30% to that wattage in order to know the minimum UPS size to get.

Keep in mind that the ratings on a UPS are typically for peak performance, and they are not designed to run those wattages all the time, so if you are constantly pushing your system you will want to move up at least one size for some breathing room.

Also keep in mind that the battery will start to loose charge after the first year, and will typically need to be replaced after 2-3 years. But you can get batteries separate, so you will not typically need to purchase a whole new UPS every 2-3 years.

For 650W APC recommends their APC Smart-UPS 1500VA LCD 120V, which retails somewhere around $600. A bit pricey, but if you live in an area where the power cuts out a lot, or you need that guarenteed up-time, then it is well worth it.

http://www.apc.com/tools/ups_selector/index.cfm

 

[CaedenV]

If you don't mind trying to burn your house down you could always do a boat or door-battery mod on an old UPS to save a lot of money... but then again, it gets a little scary doing that kind of stuff.

 

[Z1NONLY]

My 950w CyberPower did well with my TX750w power supply, overclocked Phenom X6, and SLI's GTX 560's.

There is even less strain on it now that I went with an i7 setup.

 

[virajk]

Best answer selected by virajk.

 

[virajk]

If you don't mind trying to burn your house down you could always do a boat or door-battery mod on an old UPS to save a lot of money... but then again, it gets a little scary doing that kind of stuff.

Agree, modding a UPS is indeed scary - better buy a new one than have to regret for a house burnt down !


But on a serious note - are Rosewill PSU's that bad ??

I'm from India, and electronics here are too darn expensive and I'm on a tight budget,I got the Rosewill from a friend who was in the USA, through Newegg.

 

[CaedenV]

It is not so much that Rosewill has a flawed design, or that they are all known for going dead early, it is just a matter of a lack of Quality controll and buying their products is more like playing the lottery than purchasing hardware. You might get one, and it may work great for many years. But you may also get a bad one that will either die quickly, or over/undervolt hardware causing really wierd issues for years before you figure out what is wrong.

When there are cheap Antec earthwatts products on the market which are reliable why take the chance? Even OCZ has cleaned up their act in the past few years and have some great low cost products out there.

For cables, card readers, fans, cases, and even keys and mice Rosewill makes decent cheap stuff. But any of those things dies then you just buy a new one to replace it; No big deal. But if a power supply goes then it can also take other parts out with it (like your HDD, mobo, ram, GPU, etc.), and that is not something to take lightly. Again, I am not suggesting that you go out and get some crazy high end power supply, but that is one of the few parts that you do not want to skimp out on either.

 

[virajk]

It is not so much that Rosewill has a flawed design, or that they are all known for going dead early, it is just a matter of a lack of Quality controll and buying their products is more like playing the lottery than purchasing hardware. You might get one, and it may work great for many years. But you may also get a bad one that will either die quickly, or over/undervolt hardware causing really wierd issues for years before you figure out what is wrong.

When there are cheap Antec earthwatts products on the market which are reliable why take the chance? Even OCZ has cleaned up their act in the past few years and have some great low cost products out there.

For cables, card readers, fans, cases, and even keys and mice Rosewill makes decent cheap stuff. But any of those things dies then you just buy a new one to replace it; No big deal. But if a power supply goes then it can also take other parts out with it (like your HDD, mobo, ram, GPU, etc.), and that is not something to take lightly. Again, I am not suggesting that you go out and get some crazy high end power supply, but that is one of the few parts that you do not want to skimp out on either.

K thanks !

 

[dingo07]

Here's where you can select your manufacturer and then model # of PS to check it's efficiency on a chart - http://www.plugloadsolutions.com/80PlusPowerSupplies.aspx

The system in my signature, running the Heaven DX11 benchmark pulls a max of 430W for a split second and averages about 385W. Idle it sucks 165 on average. My UPS is an APC Back-UPS Pro 1000 - http://www.apc.com/products/resource/include/techspec_index.cfm?base_sku=BR1000G&total_watts=200
I have no issues because my system never get's close to 80% of it's capacity