Will my power supply handle an HD 6670?

atroks

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Feb 12, 2013
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Hi, I`m buying a graphics card, Radeon HD6670.
I want to know if my power supply is enough or if I have to buy a new one.

My specs:
AMD Phenom II X4 910e @ 2.6GHz
4GB DDR3 RAM
Radeon HD6670 (will buy)
500GB HDD 7200RPM
1 DVD-RW drive


My previous PSU died, so I send the computer to repair and they put a 230W one, these are the specs of this PSU:


3,3V : 15A max
5V : 18A max
12V1 : 12A max
- 12V: 0.3A max
5V SB: 2,0A max


Well, can it handle the new GPU or should I buy a new PSU?

Thanks 😀
 
Try doing the calculation with this tool:
http://www.extreme.outervision.com/psucalculatorlite.jsp

From my calculation on your setup, 211W PSU should do fine, without graphics. 247W are needed for 6670, new PSU, usage 90%.

Even if it works fine at the beginning, the PSU will degrade with time.

In your place I would replace the PSU even without any graphics card. And that is assuming the PSU is worth it's money, and is not one of those cheap tin ones that will burst into flames even within rated power.
 
I plugged those specs into the pro version of that calculator, and with the 6670, you'll need 13.8 A on the +12V rail. With the 7750, you'll need 13.9 A. Definitely a bad idea to try to run those on a psu that can only provide 12 A on the +12V rail.
 

Good idea, make sure it is a quality unit. If the price seems too good to be true it is. I have seen too many 500 watt units with less power then a quality 300 watt unit. Look for the +12v AMP rating or combined +12v rating on multi rail power supplies.

Even I am not brave enough to try a 7750 on that power supply, but am running a GTX 650ti on a 300 watt power supply :)
 


I checked this one: http://www.coolermaster.com/product.php?product_id=3746

It seems ok for my needs and it`s not very expensive.
 
216 watts @ 12 volts(216/12=18amps combined), while enough(but still lower then the 300 watt I have with 22amps @ 12 volts) is still rather low for a "390 watt" power supply.

The voltage switch is more of an indicator of and older design(older designs are also less efficient).

This explains why it does not put a larger portion of its total power into the 12 volt rail(s). It in fact has little to no reason for rails since it only has 18 amps and that falls within the specs for a single rail power supply.

The multi rail idea is almost always just a current limiter(to separate a larger 12 volt rail into smaller rails. Think of it the same way your electrical panel works) to prevent a user from trying to run the full system off 1 plug with tons of adapters and splitters.

Newer power supplies use one very large 12 volt rail then split or do not split it with current limiters(it is always a debate of single vs multi rail).

Now the important part is that they also provide the 5 and 3.3 volt rails from a DC-DC converter board that is power off the 12 volt rail. This is why you can see a 850 watt power supply with 840 watts @ 12 volts yet still another 130 watts on the 3.3/5. So to some extent a system using lots of 3.3/5 volts will slightly decrease to 12 volt current. 3.3 and 5 volt rails are not heavily used on modern systems. ALL USB powered devices as well as laptop drives and parts of hard drives do use the 5 volt rail, but not too much of it.

These large 12 volt rails + 3.3/5 off that rail means that if you do need to use extra power on the 3.3/5 volt rails, you can and if you do not, you can use more 12 volt power.

In this example, every watt you pull from the lower rails will lower the 288 watt limit for the 12 volt rails. As you can see ALL rails together must NOT pass 300 watts on this power supply. You also note despite seeing 2 x 17 amp rails, the load from both must never pass 24 amps. Many users make a mistake and this that they have 34 amps. This is not true(34 x 12 = 408 watts)
multirail.jpg
 


WOW, it explained a lot, thanks!

The thing is, I won`t be needing all that power, as stated before, and my system draws very little power. The CPU draws 65W and the HD6670 draws 61W maximum.

I know this isn`t the best PSU ever, but I think it is good and safe enough for my system, I won`t be upgrading it in the near future, and the next will probably be an entirely new machine.

So, is this PSU from Cooler Master ok or should I look for another model?

Thanks 😀
 
The biggest issue is that CoolerMaster has been known to make some power supplies that fail to deliver the rated wattage.

You are correct that your system should not exceed the power supplies abilities as long as it can at least deliver close to its rated power.

To be honest. I have a hard time pushing past 150watts on my media center with most games and it has parts that should take more power then your system. I only worry about the quality of the power in this case not an actual lack of it.

 

Thanks, I think I will buy this model, or another at the same price range, I don't have a lot of money and there aren't many budget options where I live, at least Cooler Master is a known brand haha, I've seen some power supplies that I fear they will explode in the moment I touch them.