Zumax 500w PSU and the 280

[Zachary Westover]

Hi!
I have bought a ASUS R9-280. I have a Zumax 500 watt PSU.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817101011

My PSU has 2 12v rails rated @20amps each. I've read the 280 need 30 amps to the 12 volt rail. I've seen I can use the molex adapters to use each rail for the same PSU. So then the card would have 20 amps coming from two rails available. Is that a good idea or not?

I currently have an i5 3330 and a 7200rpm hardrive and 1 exhaust fan. I also 8gb of DDR3 rated at 1600mhz

Here is the link to the graphics card:

http://www.newegg.com/Product/Product.aspx?Item=N82E16814121867&nm_mc=KNC-GoogleAdwords&cm_mmc=KNC-GoogleAdwords-_-pla-_-Desktop+Graphics+Cards-_-N82E16814121867&gclid=CjwKEAjw456hBRDQ4eqg8MzA2W0SJABI2gJ8-6Sh7SSzAamsvEoa0k2Q8jnMAPZeHfzfzQUAIy5wyhoCh2Pw_wcB

 

[clutchc]

With a max of only 34A available at the +12V rails (as per the nameplate of that PSU), I would not attempt that. The R9-280 is a 250W card. That is ~21 amps for the card alone.

 

[Zachary Westover]

With a max of only 34A available at the +12V rails (as per the nameplate of that PSU), I would not attempt that. The R9-280 is a 250W card. That is ~21 amps for the card alone.

Well there are 2 12v rails rated @20Amps each. I was thinking I could use a molex adapters from the other rail so the card would be split between two rails. Which in my opinion still doesn't look like the best idea. I just need that to last a while till I can sell my current GPU and buy a better name brand PSU. Such as an EVGA or Corsair.

Also I am going to be the R9-280 not the R9-280x. Just and update.

 

[clutchc]

While each rail has a 20A capacity, the +12V combination is only rated at 34A as is spec'd out in the nameplate. (+12V1+12V2 Total Output 34A) That includes the whole +12V system, including any Molex, SATA, ATX, or CPU power cables.
Most low capacity PSUs that only come with a single PCIe 6 pin power cable do that so you don't try to overload them by using a card that requires 2 x 6 pin connectors or more.
The R9-280 is still a 200W card. Use it on that PSU at your own risk.

 

[Zachary Westover]

While each rail has a 20A capacity, the +12V combination is only rated at 34A as is spec'd out in the nameplate. (+12V1+12V2 Total Output 34A) That includes the whole +12V system, including any Molex, SATA, ATX, or CPU power cables.
Most low capacity PSUs that only come with a single PCIe 6 pin power cable do that so you don't try to overload them by using a card that requires 2 x 6 pin connectors or more.
The R9-280 is still a 200W card. Use it on that PSU at your own risk.

So even though the R9-280 is rated at 30 amps and my PSU is rated at 34 still not the best idea? I also read somewhere else that the 5V rail will take over in case the CPU isn't getting the necessary power. I might have mis-read that but if that is true I should be fine right?

Sorry if the questions sound really stupid or repetitive. I am not very educated in how PSU and the multi rail thing works.

 

[Zachary Westover]

Ok yet another revision. According to MSI which has their card running at a higher clock speed and blah blah blah. These are the power requirements of the 280: (Radeon R9-280 - 25A and a 500W psu minimum) I know my 500w PSU will be able to handle the wattage. And my intel processor barely ever goes through full load when I am just playing games. So if MSI is right my psu should will be sufficient for the time being until I get the money to buy a non multi rail design.

Also with what I've read about Multi-Rail designs, is that 2 rails will be supplying 25 amps leaving 9 amps left for everything on the 1st rail or second :/. The Hard Drive takes about 1.8 amps and 1 fan takes like 1/4 of an amp and the CPU is unknown, I am still kind of skeptical if this will be safe or not. So if anyone truly believes this will fry something important tell me please!

 

[clutchc]

The R9-280 will draw 16.67 amps at full load (200W / +12V = 16.7A: Ohm's Law), not 30A.
The 5V rail has nothing to do with the power the gfx card requires for its GPU demand. You were mis-reading something evidently.
Your i5 3330 is another 77W, your MB (25W - 80W), RAM (3W per stick), HDD (3.5w to 6W), DVD drive (15w to 27W), fans (1W to 6W each)... all running off the +12V rail(s). And that doesn't even look like an 80 plus rated PSU, meaning it will not be efficient even up to 80% of load.

The R9-280 will probably run fine on that PSU at idle, but when you are gaming and it is at load, you will experience shutdowns, re-boots, or worse... smoke coming out of your PSU. And depending on how well made the PSU is, it may take out other components when it dies.

But you seem determined to try it anyway. So I will keep my fingers crossed for you.

 

[Zachary Westover]

The R9-280 will draw 16.67 amps at full load (200W / +12V = 16.7A: Ohm's Law), not 30A.
The 5V rail has nothing to do with the power the gfx card requires for its GPU demand. You were mis-reading something evidently.
Your i5 3330 is another 77W, your MB (25W - 80W), RAM (3W per stick), HDD (3.5w to 6W), DVD drive (15w to 27W), fans (1W to 6W each)... all running off the +12V rail(s). And that doesn't even look like an 80 plus rated PSU, meaning it will not be efficient even up to 80% of load.

The R9-280 will probably run fine on that PSU at idle, but when you are gaming and it is at load, you will experience shutdowns, re-boots, or worse... smoke coming out of your PSU. And depending on how well made the PSU is, it may take out other components when it dies.

But you seem determined to try it anyway. So I will keep my fingers crossed for you.

No DVD drive 1 small 80mm fan from the OEM. I have the wattage figured out. It seems to be okay. according to Power Supply Calculator I'll be using around 411 watts with 90% load on the CPU and 100% load overall. it should be fine(I hope). I wish I had some testing environment without the possibility of screwing some major component of my PC up. If it kills the PSU that is no big deal I have a spare 300watt psu. Will just have to live off playing minecraft for a while until I can sell the GTX 650 Ti and buy a real power supply.

 

[Zachary Westover]

The R9-280 will draw 16.67 amps at full load (200W / +12V = 16.7A: Ohm's Law), not 30A.
The 5V rail has nothing to do with the power the gfx card requires for its GPU demand. You were mis-reading something evidently.
Your i5 3330 is another 77W, your MB (25W - 80W), RAM (3W per stick), HDD (3.5w to 6W), DVD drive (15w to 27W), fans (1W to 6W each)... all running off the +12V rail(s). And that doesn't even look like an 80 plus rated PSU, meaning it will not be efficient even up to 80% of load.

The R9-280 will probably run fine on that PSU at idle, but when you are gaming and it is at load, you will experience shutdowns, re-boots, or worse... smoke coming out of your PSU. And depending on how well made the PSU is, it may take out other components when it dies.

But you seem determined to try it anyway. So I will keep my fingers crossed for you.

Ok well it might be possible I could be running into some money in the near future and could buy a single rail power supply that could efficiently handle the R9-280. It means I would have to wait a while to use it but I'd be fine with that. What power supply would you recommend?

 

[Zachary Westover]

I found this and it will be in my price range. Is this good enough? http://www.newegg.com/Product/Product.aspx?Item=N82E16817438023

 

[clutchc]

I found this and it will be in my price range. Is this good enough? http://www.newegg.com/Product/Product.aspx?Item=N82E16817438023

Better than you have now, yes. At least it has a +12V rail that can handle the load.