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7850x2 psu help

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February 12, 2013 6:45:42 PM

Hi all, I haven't got a clue when it comes to psu's, I had a look at a few psu calculators online but with very conflicking results. :??: 

I have a XFX 550w pro core edition

http://www.amazon.co.uk/XFX-P1-550S-XXB9-PRO550W-Editio...

Will this psu be ok for 2x asus 7850's OC tiwn frozr's?

other specs

P8Z77-m pro
i5 2310
8gb ddr3 (2x4gb)
2 sata harddrives
2x fans
1x dvd-rw

thanks for any help!

More about : 7850x2 psu

February 12, 2013 7:16:32 PM

Hi Mattck,
Now a good quality PSU of lower power is always better that a bad quality PSU of higher powern and you have a PSU of good quality. However, most GPU manufacturers will recommend a PSU of at least 600W. This is most likely to cover their own backs and your CPU doesn't use a lot of power.
You will probably be okay with a 550W FOR NOW, however it will be under a VERY high load and if you overclock your hardware or use it heavily, it could fry completely. Please note that under max load 1 HD 7850 uses around 250W, so 2....

Personally if I had enough and was in your situation, I'd go for a 600-700W PSU. Not only will this cover your 2 7850's but it will safeguard you for upgrades in the future :)  Heres a decent 650W: http://www.scan.co.uk/products/650w-corsair-enthusiast-...

Regards,
Dan.
a b ) Power supply
February 12, 2013 7:50:19 PM

Since the 7850 overclock nicely I would move up another 100w or so but with everything running at stock a good quality 550w will do fine.

A 7850 is 100-130w under load.
Related resources
a b ) Power supply
February 12, 2013 7:56:56 PM

I have a Corsair TX750w that I have been using for 5yrs now and still running strong. You have to make sure the PSU you buy also has all the necessary PCI-E connections.
February 12, 2013 8:25:43 PM

popatim said:
Since the 7850 overclock nicely I would move up another 100w or so but with everything running at stock a good quality 550w will do fine.

A 7850 is 100-130w under load.

Yeah, sorry for the misleading info, found it on a website... I thought it was a lot though as my old HD 6850 only uses 125W!
a c 144 ) Power supply
February 13, 2013 8:07:53 AM

The 550 should work. Each 7850 only needs one PCIe cable.

You will be able to tell if you need a more powerful PSU because your system will reset and reboot under heavy graphics load - gaming, primarily.
a b ) Power supply
February 13, 2013 8:22:19 AM

That PSU should be adequate so long as you don't do any heavy overclocking or otherwise very power-consumption intensive upgrades beyond the two 7850s, but it would run the PSU at a somewhat high load during gaming. Not dangerously high, but high.
February 13, 2013 9:23:06 AM

Thanks for the help all! I think I'll stay with this then till i want to overclock them.

Thanks again!
a c 281 ) Power supply
February 13, 2013 4:14:11 PM

jsc said:
The 550 should work. Each 7850 only needs one PCIe cable.

You will be able to tell if you need a more powerful PSU because your system will reset and reboot under heavy graphics load - gaming, primarily.


I think he is referring to a non reference Asus 7850 which
might require two pci-e connectors.
a b ) Power supply
February 13, 2013 4:30:10 PM

Are you sure that they need two cables? I've known several cards that had a more advanced cable support than was necessary for running them at stock and they usually ran fine with the regular cable combination for their type of card.
a c 281 ) Power supply
February 13, 2013 4:44:05 PM

blazorthon said:
Are you sure that they need two cables? I've known several cards that had a more advanced cable support than was necessary for running them at stock and they usually ran fine with the regular cable combination for their type of card.


No - not sure - the Asus specs say up to 150w - 1additional 6 pin needed.
I don't know if "additional" means two or one.

There are non-ref 7850's that require two, but the specs are
pretty clear. On the 3 Asus models I looked at it isn't clear.
I suspect they may need only one, but the 150w made me
think twice.
a b ) Power supply
February 13, 2013 4:49:25 PM

Well, for 150W, you can get up to 75W from the PCIe slot and up to 75W from a single six-pin cable for a total of up to 150W, so it seems like they are single-cable cards.
a c 281 ) Power supply
February 13, 2013 4:56:01 PM

blazorthon said:
Well, for 150W, you can get up to 75W from the PCIe slot and up to 75W from a single six-pin cable for a total of up to 150W, so it seems like they are single-cable cards.


Most likely correct, if they hadn't used the word "additional",
I wouldn't have thot twice about it.
February 13, 2013 6:51:48 PM

Yeah, the cards only a single 6-pin, the system requirements in the msi book says 75w.

The psu actually has 1 6-pin cable, and 1 6+2-pin cable.... don't if that helps lol, as I said I haven't a clue about psu's.

the psu box says:

44A +12v

24A +3.3v

24A +5v

0.5A -12v

2.5A +5vsb

=550w

It also says its true wattage guarantee! (I don't know how true that's is lol)

So do u think it will be ok if I don't overclock?
a b ) Power supply
February 13, 2013 6:54:53 PM

I would probably want a quality 650w at minimum for dual graphics like those.
a c 281 ) Power supply
February 13, 2013 7:27:11 PM

mattck said:
Yeah, the cards only a single 6-pin, the system requirements in the msi book says 75w.

The psu actually has 1 6-pin cable, and 1 6+2-pin cable.... don't if that helps lol, as I said I haven't a clue about psu's.

the psu box says:

44A +12v

24A +3.3v

24A +5v

0.5A -12v

2.5A +5vsb

=550w

It also says its true wattage guarantee! (I don't know how true that's is lol)

So do u think it will be ok if I don't overclock?


Hi - your XFX 550w is very close to the 575w realhardtech suggests, but the
550 also has 44a on the +12v rail. 528w of the total on the
+12v rail is very good. You'll be fine, and even do moderate OC
!