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UPS not sustaining computer

C

carlwu

Member
I had a 300W APC 500 model which I replaced with an APC RS800 (800VA/540W). I have an Athlon64 system with Tagan 480W PS and 19" LCD monitor. Even when just the computer is plugged in, when power is cut, the computer abruptly looses power--as if there was no UPS!!!

It did the same with the APC500 and I thought it was because 300W was too low. With up to 540W, I thought I would have room to spare. Anyone know what's going on? The battery is kicking on because it will power my 150W torchiere lamp.

Frustrated...
 
It is unlikely than your PSU and LCD panel are gobbling all that power. Your PSU is rated up to 480W, this does not mean that it consumes that much.

However you could still be running quite close. Most 19" LCD's will consume between 40 and 50W.

Is there anything else plugged into the UPS besides the PC and Monitor.

Also once properly setup there is no need to have the monitor plugged into the UPS at all, the computer will manage to save its data and settings and perform a controlled shutdown.
 
I have even tried just the computer. It just cuts power completely. I read the Back-UPS RS800 (800VA) manual today and set the unit for "high sensitivity mode" for devices that are sensitive to voltage fluctuations. It almost seems like the Tagan does not like the switchover to battery or can sense that power is not from the wall. AFter it cut power, I tried turning the computer on (UPS is on battery now) and I can see the mobo's LED come on transiently. I'm completely stumped. It won't even hold power for a second. The UPS has been plugged in over 24 hours, well above the 8 hour charge time.

Instead of questioning the UPS, could it be the power supply or the mobo does not like the momentary switchover to battery? The mobo is DFI LanParty Ultra (nforce4).
 
Yes the battery is hooked up. Again, it powers a 150W lamp OK. When I have my computer and monitor hooked up, the monitor stays on but the computer shuts down. I have a feeling the power supply may be eating up more than the APC can dish out. It is odd to me that the computer cannot stay on for any length of time. I'm going to try hooking a bunch of lamps to the APC to see how much power I can load it down with...
 
Be careful when adding lamps, pre warm them by plugging them into the wall for a bit before plugging into the Backup - they draw a lot more for a second when they are cold than they do when up to temp...
. And how are you testing your UPS. Remember, a real power outage usually looks like almost a short across the AC side of your UPS, NOT an open circuit - even though that should really make no diff in the operation of a UPS. Try plugging a night light into one of the backed up outlets and see what happens to the light when the computer dies (if it stay lit, then it must be the shutdown management software or something else in the PC.
. So if you are using the software that came with the UPS to manage shutdown make sure it isn't set to "Immediate Shutdown" or something similar...

.bh.
 
Well..I dont seen any good answers to your question, so I will give you something more to think about. It is very likely that this is not a power issue at all. The issue with a standby UPS is that when the line power goes out, the switch to battery power happens very quickly, but not instantly. There is a delay of a fraction of a second while the switch occurs, which is called the switch time or transfer time of the UPS. While rare, it is possible for the UPS to not make the switch fast enough for the PC's power supply to continue operation uninterrupted. You should compare the unit's transfer time to the hold (or holdup) time of your power supply unit, which tells you how much time the power supply can handle having its input cut off before being interrupted. If the transfer time is much less than the hold time, the UPS will probably work for you.
 
Thanks Deathwalker. That is interesting stuff to be sure. Will look into it.

APC RS800 is going back. Thankfully, Buy.com seems to be pretty good about returns...got a return label and everything.

I emailed APC and Tagan to get their thoughts.

I did a search of the internet and one user with the Tagan TG480 power supply also had problems. Tagan recommended at minimum a 1000VA/650W UPS to him, but when he got one meeting the specs, it also didn't work. This transfer time to hold may be the problem...
 
Switching PSUs shouldn't need sine wave. I wouldn't be buying tagan on the basis of a few good reviews on fanboy sites anyways. The fanboy reviews of PSUs are generally about as reliable as a crack ho...

.bh.
 
1. The battery may take up to 8 hours to charge.
2. Make sure the computer is plugged into one of "Battery Backup" outlets. The outlets labeled "Surge Only" are for AC only surge protection.
 
Nothing wrong with Tagan480. I have one. I just pulled the plug and the UPS kept the PC and monitor going and I was able to power down.
 
Your UPS should be able to handle that load. I have an APC 750VA UPS...I don't know if it was ever released--I had to RMA my brand new noisy 725VA and APC sent me a quiet 750VA unit.

Anyway, the 750VA powers my Viewsonic 19" CRT, my Netgear MR814 wireless router, and my system for about 10-15 minutes:

Abit NF7-S 2.0
Athlon XP 2500+ w/Retail hsf
Kingston 2x512mb HyperX PC3200
ATI Radeon 9800 Pro 128mb
Sound Blaster Audigy 2 ZS
Western Digital 74gb Raptor
Black NEC 3500A 16x DVD+/-RW
Black Lite-On 52x32x52x16 Combo Drive
Blue 6" Cold Cathode
Logitech Elite keyboard
Logitech MX500 w/modded blue LED
Enermax 460W blue dual fan PSU
 
Navid, what UPS (brand and model) do you have?

I have an APC 500VA UPS and then bought the APC 800VA UPS and both do the same thing ie. no worky. The 500VA UPS definitely did work with my older system (Sparkle 350W ps).
 
Originally posted by: carlwu
Navid, what UPS (brand and model) do you have?

I have an APC 500VA UPS and then bought the APC 800VA UPS and both do the same thing ie. no worky. The 500VA UPS definitely did work with my older system (Sparkle 350W ps).
Click to expand...

I have an inadequate APC 350VA.
http://www.apcc.com/resource/include/techspec_index.cfm?base_sku=BE350U
I am in the market for a higher power one since I am overloading it. Yet, it does keep the computer and monitor going for a minute and a half! It definitely does not cause the PC to turn off.

You know that some of the plugs on the UPS are only surge protected but are not powered by the battery. You have hooked up the PC to one that is backed up, right?

Do you have your old PSU?
May be some Tagans have the problem, not all!

What exactly do you have in your PC?
It would help a lot if you had a device that could measure the power drawn by the PC.

What happens if you power down you PC and monitor? Then, pull the plug on the fully charged UPS. Then, turn on the monitor and the PC. Will the PC turn on?
 
Geez! 350VA and APC to boot!

I don't know what the deal could be. I am not a complete noob to UPS's and definitely allowed for sufficient charge time and connected the computer to the battery outlets.

My PC is pretty basic: DFI lanparty Ultra, Athlon64 3200+, 6600GT vid, 3 hd's, 1 DVD.

When unplugged and with the computer off, attempting to turn the computer on results in the mobo LED's/case fans going on for about 1/2 sec before becoming dead. The PC does not come close to booting up.

I actually only need about 10minutes of UPS time too. I get a lot of transient (<2minute) blackouts during heavy storms.
 
Do you have another PSU?
Do you have your old PSU?

If you do, the best way to move forward may be to replace the PSU and try again. If it works, it is obvious that something is wrong with Tagan. If it still does not work, it means that the problem very likely is somewhere else.
 
I actually still have my previous computer with the Sparkle. It has and still works with the APC. I don't really want to swap in the Sparkle for the Tagan. Seeing how I am not the only one with a Tagan that can't be powered by a reasonable UPS, I'm thinking it is the TAgan causing the trouble.
 
Originally posted by: carlwu
I actually still have my previous computer with the Sparkle. It has and still works with the APC. I don't really want to swap in the Sparkle for the Tagan.
Click to expand...
Then don't unplug the UPS or have the PC running during a storm. 😛

 
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