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Errr.... I don't have 30 Amps for my video card

Last response: in Graphics & Displays
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September 19, 2007 11:16:35 PM

I bought an Acbel 600W power supply ("85% Energy Efficient"), thinking it'd be enough to run my 2900XT. Since I had no plans to run it in crossfire, I didn't worry/research too much about power requirements. I felt sure 600W from a decent brand was good enough for any single card.

Well, once I got home I noticed that the instruction manual recommends 30A current on 12V rails. Funny, nowhere in the 2900XT box exterior did it say that.

I look at the sticker in my power supply, and sure enough under "+12V1", "+12V2", and "+12V3" is written 20A. I'm using a pair of 2x3 connection pins from the power supply to the graphics card.

Is this going to be a problem?

More about : errr amps video card

September 19, 2007 11:38:51 PM

It SHOULD run, however I recommend getting a PSU from a decent brand as you said, not unknown like "Acbel". Try something like Seasonic M12 or S12, Corsair VX or HX, Antec NeoHE, PC Power & Cooling Silencer units to be safe.
September 19, 2007 11:44:22 PM

See if it's one of these:
Acbel ATX-450A2 25amps
Acbel ATX-500CA 27amps
Acbel R8 Power API5PC36 25amps
Acbel R8 Power API5PC37 30amps
Acbel R8 Power API5PC38 37amps
Acbel Intelligent Power 5PC04 35amps
Acbel LCD Power API5PC03 SLI 34amps
Acbel LCD Power API5PC04 SLI 35amps
Related resources
September 20, 2007 12:05:44 AM

That's normal, I think you use the combined 12v rail voltage. Actually it's not as simple as adding them up and I must admit I don't fully understand. But the total available will be higher than what's on a single rail I do believe. I have a kick a** PSU and it only shows 18a each under the 12v 1 2 and 3. It runs my 8800 gts and a bunch of other stuff just fine.

As was mentioned above as long as the minimum power specs are met you 'should' be OK. But anytime you have an off-brand PSU of questionable quality all bets are off as to how well and how long it will work.
September 20, 2007 12:08:41 AM

kpo6969 said:
See if it's one of these:
Acbel ATX-450A2 25amps
Acbel ATX-500CA 27amps
Acbel R8 Power API5PC36 25amps
Acbel R8 Power API5PC37 30amps
Acbel R8 Power API5PC38 37amps
Acbel Intelligent Power 5PC04 35amps
Acbel LCD Power API5PC03 SLI 34amps
Acbel LCD Power API5PC04 SLI 35amps



That's the one! Model Number API5PC38. Although I don't know where you got the 37amps from. The sticker label on the PSU unit itself clearly states 20A on those +12V lines. Am I to assume that a pair of those +12V connectors yields 37 amps?

I just bought the PSU unit earlier this week, and I could have it exchanged if it's inadequate for the Radeon 2900 XT.

These graphics cards really ought to have their hardware requiremnts explicitly written on the exterior of the box. That would've saved me from some trouble.
September 20, 2007 12:21:01 AM

Even though it seems powerful enough, I would exchange it for a more reputable brand. Like the ones I mentioned above.

And they do have their requirements written on the outside of the box, you just got to look for them, and by now, most people that buy graphics cards should know to check that their PSUs are powerful enough to do the job.
September 20, 2007 2:00:41 AM

summer_of_alvin said:
I bought an Acbel 600W power supply ("85% Energy Efficient"), thinking it'd be enough to run my 2900XT. Since I had no plans to run it in crossfire, I didn't worry/research too much about power requirements. I felt sure 600W from a decent brand was good enough for any single card.

Well, once I got home I noticed that the instruction manual recommends 30A current on 12V rails. Funny, nowhere in the 2900XT box exterior did it say that.

I look at the sticker in my power supply, and sure enough under "+12V1", "+12V2", and "+12V3" is written 20A. I'm using a pair of 2x3 connection pins from the power supply to the graphics card.

Is this going to be a problem?


Hey Alvin. I have never heard of that power supply manufacturer before, but looking at the PDF, the specs look good. I would just use it for a while and find out.

Regarding the +12v rail thing. You have a tri-rail unit with 20a per rail. To get the sustained/continuous amperage on the combined +12v rails, you take the total wattage of the 3 rails and divide by 12. Pretty simple equation but you need to depend on the manufacturer to provide the info. I downloaded the PDF from AcBel and unfortunately they don't list the wattage only mV, which is the same thing Antec does. So I can't give you an exact figure, just a guess. It probably has anywhere from 35a-45a on the +12v rails combined.

Also, just to give you a real world example, my power supply is a dual-rail unit which has 20a on both rails. The total wattage for both +12v rails is 432w which is on the label and can also be found on the Enermax site. So, 432 divided by 12 = 36. So I have 36a of sustained/continuous power on the combined +12v rails. Again, not hard to figure out as long as you know the wattage on the +12v rails and perhaps that's what the 37a is that kpo6969 referred to.

Normally, I recommend either a Corsair or Enermax, but I would try your current PSU out for a while. If you don't have any game crashes or stability issues, your fine. Oh, you should also use 2 - 6 pin PCI-E connectors to power the card. The PDF I looked at says you have 2 since the power supply is labeled SLI Ready.

Here's a link to their site where I downloaded the PDF ......

http://www.acbel.com/html/products_/pc_1.htm

Good Luck
September 20, 2007 4:18:23 AM

summer_of_alvin said:
That's the one! Model Number API5PC38. Although I don't know where you got the 37amps from. The sticker label on the PSU unit itself clearly states 20A on those +12V lines. Am I to assume that a pair of those +12V connectors yields 37 amps?

I just bought the PSU unit earlier this week, and I could have it exchanged if it's inadequate for the Radeon 2900 XT.

These graphics cards really ought to have their hardware requiremnts explicitly written on the exterior of the box. That would've saved me from some trouble.


http://forums.guru3d.com/showthread.php?t=205763

"These graphics cards really ought to have their hardware requiremnts explicitly written on the exterior of the box. That would've saved me from some trouble."

http://www.atomicmpc.com.au/forums.asp?s=2&c=7&t=9354
September 20, 2007 12:49:02 PM

kpo6969 said:
http://forums.guru3d.com/showthread.php?t=205763

"These graphics cards really ought to have their hardware requiremnts explicitly written on the exterior of the box. That would've saved me from some trouble."

http://www.atomicmpc.com.au/forums.asp?s=2&c=7&t=9354



Yeah, would have saved me a lot of trouble as well and thanks for the Guru3D link. I'm always trying to help people out hunting down their PSU specs and doing the math myself. Great to have this power supply list a mouse click away.
September 20, 2007 7:42:48 PM

honestjohn_ said:
Yeah, would have saved me a lot of trouble as well and thanks for the Guru3D link. I'm always trying to help people out hunting down their PSU specs and doing the math myself. Great to have this power supply list a mouse click away.

No problem, I picked up a few things from you myself.
September 20, 2007 9:04:23 PM

kpo6969 said:
No problem, I picked up a few things from you myself.


Sorry, guess the good news is, now-a-days they have shots for almost everything :ange:  ......
September 21, 2007 3:40:45 PM

honestjohn_ said:
Hey Alvin. I have never heard of that power supply manufacturer before, but looking at the PDF, the specs look good. I would just use it for a while and find out.



I did some research on the Acbel brand before I bought the PSU. Apparently, Acbel is the OEM brand/manufacturer for some of the Cooler Master PSUs (ie Real Power series). So I guess they're not so bad.

Anyway thanks to everyone for their very helpful advice, especially honestjohn_ and kpo6969. I was afraid I had made a mistake by haphazardly choosing a PSU based on wattage alone. Fortunately, my rig is running perfectly fine so I feel a bit better about it now :) 
September 21, 2007 3:57:44 PM

summer_of_alvin said:
I did some research on the Acbel brand before I bought the PSU. Apparently, Acbel is the OEM brand/manufacturer for some of the Cooler Master PSUs (ie Real Power series). So I guess they're not so bad.

Anyway thanks to everyone for their very helpful advice, especially honestjohn_ and kpo6969. I was afraid I had made a mistake by haphazardly choosing a PSU based on wattage alone. Fortunately, my rig is running perfectly fine so I feel a bit better about it now :) 


No prob. Enjoy the card and welcome to the 2900XT club. :hello:  We'll be holding a meeting next week in the Pizza Hut off exit 13a of the NJ Turnpike if you wish to attend. We have a table for 6 reserved. :o 
!