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Check your amps! A harsh lesson learned.

Last response: in Graphics & Displays
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February 26, 2013 12:13:12 AM

So, some of you might remember a small thread I made a couple of days ago about my GPU dying on me. Well, the replacement came in today. Now, I got a 9800GT with the intention of it being a temporary card to hold me over until I could afford a better one. My PSU was a year old and 650 watt. The 9800GT recommends 430, not to mention that it's what? Five or six years old?

The new card got here today, I put it in, hooked everything back up and powered on. Installed the latest drivers, temps looked great, I even loaded up WoW to see how it'd do under load. Well, around an hour and a half in the PC suddenly shuts down and will not turn back on. Plus, I could smell the distinct odor of burnt electronics. My PSU is fried. Why? The 9800GT requires 26 amps on the 12v+ rail. My PSU had 20. Now, I'm sitting with my fingers crossed that it didn't take anything with it since it shut itself off. It didn't shoot sparks or blow up, just shut down. Long story short, and a good lesson learned? Make sure your PSU can handle your GPU even if you're well over the watt requirements.
a b U Graphics card
February 26, 2013 12:32:11 AM

Not to mention as PSU's age they start losing their ability to supply their rated current as cap's slowly wear and what not.
PSU's are one of those things that usage and age really takes their toll on too
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February 26, 2013 12:40:54 AM

This is true, although I didn't consider it because it's just a year old. I'm just incredibly concerned about everything else now. If it took out anything else, I'd be left without a PC at all.
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a c 172 U Graphics card
a b Ý World of Warcraft
February 26, 2013 12:41:59 AM

many of us have learned this lesson before. dont cheap out on the psu or you will regret it and stick to reputable brands. Some cheap psu's labeled 600w actually can only produce 300w under a continuous load. the 600w they produce is upon explosion and a puff of smoke.
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a b U Graphics card
February 26, 2013 12:43:01 AM

I doubt it was aging after only a year. What was the make and model? Need any suggestions for the new one?
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February 26, 2013 12:44:39 AM

Luckily, there was neither explosion nor smoke. Just a total shutdown and that electronic burnt smell. Surprisingly, the fan on the PSU spun the entire time until it shut off.
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February 26, 2013 12:47:22 AM

jnkweaver said:
I doubt it was aging after only a year. What was the make and model? Need any suggestions for the new one?


No, it wasn't age. It was under amped for that video card. It's not a known brand, I had it installed at a well respected and local repair shop. I'm going with an actual named brand now though and putting it in myself this time.
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a b U Graphics card
a b Ý World of Warcraft
February 26, 2013 12:50:13 AM

Makes me wary of my older PSU's and putting in new cards in older rigs, even if not under specced, the near max rail draw may cuse issues

fyi I had a thermaltake 430W and that had 18 amps on the 12v rail by itself

I would get this, its cheap and reliable buy right now

http://pcpartpicker.com/part/corsair-power-supply-cx500
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a b U Graphics card
February 26, 2013 12:51:41 AM

BeardedGent said:
My PSU is fried. Why? The 9800GT requires 26 amps on the 12v+ rail. My PSU had 20.

This is incorrect. The 9800 GT max TDP is 105 watts. At 12 volts, the maximum draw is 8.75 amps.

You had something else go wrong. What brand was this 650W power supply? It should have way more than 20 amps on the 12 volt rail.
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February 26, 2013 12:58:29 AM

tigerg said:
This is incorrect. The 9800 GT max TDP is 105 watts. At 12 volts, the maximum draw is 8.75 amps.

You had something else go wrong. What brand was this 650W power supply? It should have way more than 20 amps on the 12 volt rail.


Zuma. I'm looking at it. It says 650w max, 12v 1 and 2 at 20amps. Model number is ZU650W. Card on newegg does specify 26amps.
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a b U Graphics card
a b Ý World of Warcraft
February 26, 2013 12:58:32 AM

tigerg said:
This is incorrect. The 9800 GT max TDP is 105 watts. At 12 volts, the maximum draw is 8.75 amps.

You had something else go wrong. What brand was this 650W power supply? It should have way more than 20 amps on the 12 volt rail.


TDP is just the thermal dissipation

its should not stress out the the 20 amps on 12v = 240W and the cpu is usually on a separate rail in dual rail PSU's

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a b U Graphics card
February 26, 2013 1:11:33 AM

stickmansam said:
TDP is just the thermal dissipation
http://www.xbitlabs.com/images/video/msi-9800gt/msi9800gt_power.gif

I know... but it's the number that is important. The 9800 GT is limited to only draw up to 105 watts, hence the TDP rating. The BIOS/firmware won't allow the card to draw more. Therefore, the max current the card will ever draw is 8.75 amps.
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a c 272 U Graphics card
February 26, 2013 1:12:31 AM

BeardedGent said:
The 9800GT requires 26 amps on the 12v+ rail.


If that were the case then that would have the card consuming 312w, that's not going to happen with 75w being supplied by the PCIe slot and 75w being supplied by the single six pin power connector from the PSU.
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a b U Graphics card
a b Ý World of Warcraft
February 26, 2013 1:20:56 AM

tigerg said:
I know... but it's the number that is important. The 9800 GT is limited to only draw up to 105 watts, hence the TDP rating. The BIOS/firmware won't allow the card to draw more. Therefore, the max current the card will ever draw is 8.75 amps.


True that but TDP is overly safe sometimes :p 
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February 26, 2013 1:21:41 AM

Mousemonkey said:
If that were the case then that would have the card consuming 312w, that's not going to happen with 75w being supplied by the PCIe slot and 75w being supplied by the single six pin power connector from the PSU.


Here's the video card. http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Look in the details for power requirements.
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a b U Graphics card
February 26, 2013 1:22:33 AM

BeardedGent said:
Zuma. I'm looking at it. It says 650w max, 12v 1 and 2 at 20amps. Model number is ZU650W. Card on newegg does specify 26amps.

Zuma is not a reliable brand. That's probably why it blew up on you, unfortunately.

As for the 26 amps.... you're reading Newegg wrong. That 26 amps is the minimum requirement for the POWER SUPPLY, not the card.

From the specs of the only 9800 GT on Newegg (http://www.newegg.com/Product/Product.aspx?Item=N82E168...)....

"Minimum of a 400 Watt power supply. (Minimum recommended power supply with +12 Volt current rating of 26 Amps.)"
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a b U Graphics card
a b Ý World of Warcraft
February 26, 2013 1:25:11 AM

^ Yep, means that they want you to have 26amps at least to run the GPU + the rest of the build
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February 26, 2013 1:35:21 AM

stickmansam said:
^ Yep, means that they want you to have 26amps at least to run the GPU + the rest of the build


That puts the blown PSU at 6 amps short (if it's even labeled correctly).
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a b U Graphics card
February 26, 2013 1:39:59 AM

BeardedGent said:
That puts the blown PSU at 6 amps short (if it's even labeled correctly).

Look dude, your 9800 GT only draws 8.75 amps MAXIMUM. The newegg specs are saying you need a power supply that can push out at least 26 amps on the 12 volt rail. Your card can only consume 8.75 of those 26. You had a PSU that SHOULD have been able to push out much more than 26 amps, more like 50+. Your card did not draw too much power to blow up the PSU. The PSU died because it was a crappy brand or some other reason. But NOT because your 9800 GT drew 26 amps!
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February 26, 2013 1:52:14 AM

tigerg said:
Look dude, your 9800 GT only draws 8.75 amps MAXIMUM. The newegg specs are saying you need a power supply that can push out at least 26 amps on the 12 volt rail. Your card can only consume 8.75 of those 26. You had a PSU that SHOULD have been able to push out much more than 26 amps, more like 50+. Your card did not draw too much power to blow up the PSU. The PSU died because it was a crappy brand or some other reason. But NOT because your 9800 GT drew 26 amps!


I realize the PSU is a PoS. I also realize that I read the description wrong. I am new to this so your hostility isn't needed. And, no, that PSU shouldn't be able to push that much. I'm betting it isn't even correct in what it does list. You can bet that I won't be going through that repair shop again. As I said, I'm doing it myself. Also, it did run my old 5770HD without issues since 2011. But, obviously it didn't have the same recommendations.
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a b U Graphics card
February 26, 2013 1:53:38 AM

BeardedGent said:
Surprisingly, the fan on the PSU spun the entire time until it shut off.

Update the thread when fixed.
It turn out to be something else, like a bad motherboard and the PSU is fine.
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a b U Graphics card
a b Ý World of Warcraft
February 26, 2013 2:05:58 AM

You have 2 12v rails 20a on 12v1 and 20a on 12v2 for a total of 40a (way more than 26 needed in the suggested PSU)

The CPU is on either 12v1 or 12v2 sometimes with the motherboard so has 20a all for itself

The GPU is on the other one with 20a for hdd, mb, fans and gpu
20-9 = 11 amps for everything else which is plenty
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a b U Graphics card
February 26, 2013 2:11:37 AM

BeardedGent said:
I realize the PSU is a PoS. I also realize that I read the description wrong. I am new to this so your hostility isn't needed. And, no, that PSU shouldn't be able to push that much. I'm betting it isn't even correct in what it does list. You can bet that I won't be going through that repair shop again. As I said, I'm doing it myself. Also, it did run my old 5770HD without issues since 2011. But, obviously it didn't have the same recommendations.

Not trying to be hostile, but a few of us told you what was up but you kept ignoring us. No worries though. We all learn from being here.

Sorry it blew up on you. Hopefully nothing else was damaged.
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a b U Graphics card
February 26, 2013 2:36:28 AM

Some notes on a top quality supply.

One, has the full rated power all available in the +12V supply, that is, a 600W supply will have 50A available on the +12V rail, a 900W supply has 75A, etc.

Two, has a single +12V rail. No splitting the power between domains. Makes things easier.

Three, is full or semi modular to reduce case clutter.

Four, should be gold or platinum efficiency for longer life, cooler and quieter running.

Five, should be a top quality brand with solid Japanese caps. Seasonic, Rosewell Lazer, Corsair, Silverstone, etc.
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February 26, 2013 2:46:02 AM

tigerg said:
Not trying to be hostile, but a few of us told you what was up but you kept ignoring us. No worries though. We all learn from being here.

Sorry it blew up on you. Hopefully nothing else was damaged.


It wasn't so much ignoring as not comprehending what was being said. I also didn't realize that you took both 1 & 2 into consideration when looking at the total amps (20 on 1 and 20 on 2). Actually, now that I think about it, when I first booted the PC on, it made an awful noise. Vibrated the case as well. It stopped after a moment. I have to wonder if that was t the fan on the PSU or something.
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a c 266 U Graphics card
a b Ý World of Warcraft
February 26, 2013 3:15:54 AM

The power output on each of the 12v1 and 12v2 rails is an artificial UL limit for safety reasons. Behind that, there is really only one power generating rail.
Normally, you can't simply add the amps of the two rails together to get the maximum available 12v. amps. It is usually something less from less capable brands.
A reputable brand will state the maximum combined power for 12v, expressed either in amps, or watts(then divide by 12v)

A pci-e slot can deliver up to 75w or 6.25a. If a graphics card needs a 6 pin auxiliary connector, thet can deliver another 75w or 6.25a. A 8 pin connector can deliver 150w or 12.5a. That is maximum.

The problem with cheap power supplies is several fold:
1. The power or wattage may be delivered on other than the 12v rails where it is needed most.
2. The power may be specified as a maximum or peak, not a continuous power.
3. The power may be delivered at 20c, room temperature, not the 40c or more that might be found installed in a case.
4. A cheap psu will lack some of the protections of a better unit and may cause damage to other parts if it fails.

Here is a nice list of psu's sorted by quality tiers for future guidance:
http://www.eggxpert.com/forums/thread/323050.aspx

It is the graphics card configuration that largely determines how much power you need.
This handy sizingchart assumes a normal complement of cpu and peripherals:
http://www.realhardtechx.com/index_archivos/Page362.htm

Hope this helps.
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a c 172 U Graphics card
a b Ý World of Warcraft
February 26, 2013 3:48:20 AM

babernet_1 said:
Some notes on a top quality supply.

One, has the full rated power all available in the +12V supply, that is, a 600W supply will have 50A available on the +12V rail, a 900W supply has 75A, etc.

Two, has a single +12V rail. No splitting the power between domains. Makes things easier.

Three, is full or semi modular to reduce case clutter.

Four, should be gold or platinum efficiency for longer life, cooler and quieter running.

Five, should be a top quality brand with solid Japanese caps. Seasonic, Rosewell Lazer, Corsair, Silverstone, etc.

a top quality psu does not have to have one single 12v rail. thats stupid. in a multi 12v rail psu they do not unevenly distribute power among the power cables unless its a cheap piece of crap. And you dont need solid caps, and it doesnt have to be modular. What you are describing with those features are the most expensive power supplies around, which arent needed for a 9800gt, for christ sake they will cost way more than the value of the card. read a decent article like these to get yourself the facts
http://www.jonnyguru.com/forums/showthread.php?t=3990
http://www.hardwaresecrets.com/article/Hardware-Secrets...
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a b U Graphics card
a b Ý World of Warcraft
February 26, 2013 3:54:09 AM

Solid caps are awesome though, no more bursting electrolyte messing things all up, half of my hardware failures were due to those :) 

Yep, modular is a bonus if you have the cash and Bronze/Silver is plenty already
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a b U Graphics card
February 26, 2013 1:27:33 PM

geofelt said:
The power output on each of the 12v1 and 12v2 rails is an artificial UL limit for safety reasons. Behind that, there is really only one power generating rail.
Normally, you can't simply add the amps of the two rails together to get the maximum available 12v. amps. It is usually something less from less capable brands.
A reputable brand will state the maximum combined power for 12v, expressed either in amps, or watts(then divide by 12v)

A pci-e slot can deliver up to 75w or 6.25a. If a graphics card needs a 6 pin auxiliary connector, thet can deliver another 75w or 6.25a. A 8 pin connector can deliver 150w or 12.5a. That is maximum.

The problem with cheap power supplies is several fold:
1. The power or wattage may be delivered on other than the 12v rails where it is needed most.
2. The power may be specified as a maximum or peak, not a continuous power.
3. The power may be delivered at 20c, room temperature, not the 40c or more that might be found installed in a case.
4. A cheap psu will lack some of the protections of a better unit and may cause damage to other parts if it fails.

Here is a nice list of psu's sorted by quality tiers for future guidance:
http://www.eggxpert.com/forums/thread/323050.aspx

It is the graphics card configuration that largely determines how much power you need.
This handy sizingchart assumes a normal complement of cpu and peripherals:
http://www.realhardtechx.com/index_archivos/Page362.htm

Hope this helps.


Thanks for the links. I needed those for my bag of tricks.
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February 26, 2013 2:29:05 PM

jnkweaver said:
Thanks for the links. I needed those for my bag of tricks.


Indeed, bookmarked for future use. Quick update. The inside facing fan on the old PSU gave out. Now, when that happened, who knows but that was most likely the cause of the sudden burn out. I'm dropping a Cooler Master 750 watt with 60 amps in it when it gets here. I'm going with Cooler Master at the recommendation of a friend who's used one for years. Miles may vary, of course. Fingers crossed that there was no damage done elsewhere.
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a c 172 U Graphics card
a b Ý World of Warcraft
February 26, 2013 7:50:10 PM

i would never go with cooler master. they do make a few good models, but the good ones are abour 10% of their entire range. Stick with Antec, Seasonic, XFX or Corsair, they do not have any poor models, but obviously the more expensive models have better specs.
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a b U Graphics card
a b Ý World of Warcraft
February 26, 2013 8:12:10 PM

CX500 and CX600 are good cheap starting points to looking for PSU's
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a b U Graphics card
February 26, 2013 8:41:56 PM

BeardedGent said:
Zuma. I'm looking at it. It says 650w max, 12v 1 and 2 at 20amps. Model number is ZU650W. Card on newegg does specify 26amps.



No he's right.

Math (75w+75W) / 12v = 12.5amps under full load (and I doubt under most, if not all circumstances, it will never need that).

Spec #'s generously figure in system load and in this case recommended 26amps. But this doesn't mean it needed it. A Radeon 6990 for example needs 31.25amps under load. (150w+150w+75w) / 12v = 31.25...

In the end, the psu took a dump.

Here,

Database of manufactures, their OEM's (or not) and reviews.

http://www.realhardtechx.com/index_archivos/Page447.htm

Mousemonkey said:
If that were the case then that would have the card consuming 312w, that's not going to happen with 75w being supplied by the PCIe slot and 75w being supplied by the single six pin power connector from the PSU.


+1
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