Sign in with
Sign up | Sign in
Your question
Closed

Hooking up power supply to new card (cable issues)

Last response: in Graphics & Displays
Share
December 29, 2012 5:51:11 PM

I recently bought a new video card (sapphire 7950 oc), and it has two 8 pin connections for the power supply. My power supply (which is about 2.5 years old) only has one 8 pin to 8 pin and another 8 pin to 6 pin cable.

Microcenter didn't have any 8 pin to 8 pin cables, but I was told that my 8 pin to 6 pin cable would be fine. Is this true? Or would I be able to buy a 6 pin to 8 pin adaptor and would that be okay (it sounds like it wouldn't be, but maybe?)?

Thanks!
a b U Graphics card
December 29, 2012 6:01:14 PM

Modestvolta said:
I recently bought a new video card (sapphire 7950 oc), and it has two 8 pin connections for the power supply. My power supply (which is about 2.5 years old) only has one 8 pin to 8 pin and another 8 pin to 6 pin cable.

Microcenter didn't have any 8 pin to 8 pin cables, but I was told that my 8 pin to 6 pin cable would be fine. Is this true? Or would I be able to buy a 6 pin to 8 pin adaptor and would that be okay (it sounds like it wouldn't be, but maybe?)?

Thanks!



What is the model of your power supply?


You have a couple of options:



http://www.newegg.com/Product/Product.aspx?Item=N82E168...


http://www.newegg.com/Product/Product.aspx?Item=N82E168...

http://www.newegg.com/Product/Product.aspx?Item=N82E168...
December 29, 2012 6:08:54 PM

It's a OCZ 700W - not sure about specific model. The 3rd link looks the closest to what I think I'm looking for but is there a 8 pin to 8 pin cable like that?
Related resources
a b U Graphics card
December 29, 2012 6:17:11 PM

Modestvolta said:
It's a OCZ 700W - not sure about specific model. The 3rd link looks the closest to what I think I'm looking for but is there a 8 pin to 8 pin cable like that?



Your power supply has a sinlge 8 pin, and a 6 pin right?

The GPU has 2 8 pin slots correct?

Then just plug in the 8 pin, then adapt the 6 pin into the other 8 pin with the 6 pin to 8 pin adapter.


Or am I missing something?
December 29, 2012 6:20:18 PM

The power supply has two 8 pin slots, but only one 8 pin to 8 pin cable. (The other free cable is a 8 pin to 6 pin.) The GPU has two 8 pin slots.
a b U Graphics card
December 29, 2012 6:26:08 PM

Modestvolta said:
The power supply has two 8 pin slots, but only one 8 pin to 8 pin cable. (The other free cable is a 8 pin to 6 pin.) The GPU has two 8 pin slots.



OK, now I see, it is a modular design power supply.

The box the power supply came with should have all the cables...


If it didn't then:


http://www.moddiy.com/products/OCZ-Modular-PSU-8%252dPi...


This is what you need?
a c 502 U Graphics card
a c 1104 ) Power supply
December 29, 2012 6:31:19 PM

From your description of the PSU you have the ModXStream Pro 700W - OCZ700MXSP.

There's a reason why only one 8-pin and one 6-pin PCI-E modular cables were included. It has to do with the rather weak +12V rails (i.e. ~78% of the PSU's total capacity) when compared to a decent 700 Watt PSU (i.e. ~95% of the PSU's total capacity).

Both PCI-E modular connectors on the PSU are connected to the +12V2 rail that is shared with the 4-pin Molex peripheral, SATA and floppy diskette drive power connectors.

If OCZ had included a (6+2)-pin modular cable in place of the 6-pin PCI-E modular cable then there is a very likely possibility that the 25 Amp max on the +12V2 rail would be exceeded and trigger the Over Current Protection circuit shutting down the PSU.
December 29, 2012 6:32:21 PM

Close! (I bought the same thing - an extension cable - at Microcenter but no luck) I did find the actual cable at that site for anyone interested:

http://www.moddiy.com/products/OCZ-Modular-PSU-8%252dPi...

Do you have any experience with buying from moddiy? Is shipping reasonably fast?

And bummer - I kept all the cables but I guess OCZ thought a 8 pin to 6 pin would suffice... Oh well. Thanks!
December 29, 2012 6:34:44 PM

@ko888: so is your post suggesting a new power supply in order to run this card or that I should use the 8 pin to 6 pin cable on the video card? Or something else entirely?

Btw: that's the exact power supply - nice call
a b U Graphics card
December 29, 2012 6:46:13 PM

Modestvolta said:
Close! (I bought the same thing - an extension cable - at Microcenter but no luck) I did find the actual cable at that site for anyone interested:

http://www.moddiy.com/products/OCZ-Modular-PSU-8%252dPi...

Do you have any experience with buying from moddiy? Is shipping reasonably fast?

And bummer - I kept all the cables but I guess OCZ thought a 8 pin to 6 pin would suffice... Oh well. Thanks!




http://www.overclock.net/t/1232860/moddiy-store


They ship from hong kong, people ordering from there have had positive experiences it seems.

They seem to have good prices too.
a c 502 U Graphics card
a c 1104 ) Power supply
December 29, 2012 7:07:03 PM

Modestvolta said:
@ko888: so is your post suggesting a new power supply in order to run this card or that I should use the 8 pin to 6 pin cable on the video card? Or something else entirely?

Btw: that's the exact power supply - nice call

I found the OEM's model, the High Power (Sirtec) HP-700-G14C, that the OCZ ModXStream Pro 700W - OCZ700MXSP is based on. They include two (6+2)-pin PCI-E modular cables with their version.

OCZ may have cheaped out or they're trying to avoid having to deal with possible customer calls related to the possible overloading of that +12V2 rail.

I looked up the actual power consumption of the Sapphire Radeon HD 7950 OC 3 GB and I don't see you running into any problems if you don't run FurMark while the card is manually overclocked and you just stick to gaming.

You can contact OCZ and ask for a (6+2)-pin modular cable for the OCZ700MXSP. Tell them you lost your original one.

Or try getting one of these: http://www.amazon.com/StarTech-Express-Power-Adapter-PC...
December 29, 2012 7:16:55 PM

Hmm... Good to know.

So in summary: don't use the 8 pin to 6 pin cable but if I can find a 8 pin to 8 pin cable then my current PSU should be fine? (Even though I may have gotten it in my head to go ahead and just get a new power supply... Do you think that corsair [850 watt] would be able to handle crossfire two 7950s if I decide to do that down the line?)

Thanks!

Best solution

a c 502 U Graphics card
a c 1104 ) Power supply
December 29, 2012 7:30:44 PM
Share

Modestvolta said:
Hmm... Good to know.

So in summary: don't use the 8 pin to 6 pin cable but if I can find a 8 pin to 8 pin cable then my current PSU should be fine? (Even though I may have gotten it in my head to go ahead and just get a new power supply... Do you think that corsair [850 watt] would be able to handle crossfire two 7950s if I decide to do that down the line?)

Thanks!

For a system using two Sapphire Radeon HD 7950 OC 3 GB graphics cards in 2-way CrossFireX mode AMD specifies a minimum of an 700 Watt or greater power supply. The power supply should also have a combined +12 Volt continuous current rating of 52 Amps or greater and have at least two 6-pin and two 8-pin PCI Express supplementary power connectors.

Total Power Supply Wattage is NOT the crucial factor in power supply selection!!! Sufficient Total Combined Continuous Power/Current Available on the +12V Rail(s) rated at 45°C - 50°C ambient temperature, is the most critical factor.

You may find power supplies on the market that supply more than enough Wattage to run the system. However, some of them lack Sufficient Amperage capacity on the critical +12 Volt rail, which is necessary to properly power the critical components in the system (i.e. CPU and GPUs). This is the reason why graphics card manufacturers overstate the power supply wattage, usually by at least 50 Watts, in an attempt to take into account some of those power supplies that have the weaker +12 Volt rail(s).

The PC Power & Cooling Silencer Mk II 750 Watt (PPCMK2S750), with its combined +12 Volt continuous current rating of 62 Amps and with two 6-pin and two (6+2)-pin PCI Express supplementary power connectors, is more than sufficient to power your system configuration with two Sapphire Radeon HD 7950 OC 3 GB in 2-way CrossFire mode.

The Corsair Enthusiast Series TX850 V2 (CMPSU-850TXV2), with its combined +12 Volt continuous current rating of 70 Amps and with four (6+2)-pin PCI Express supplementary power connectors, is more than sufficient to power your system configuration with two Sapphire Radeon HD 7950 OC 3 GB in 2-way CrossFire mode.

So either of your two choices are more than sufficient to do the job.
a c 91 U Graphics card
a b ) Power supply
December 29, 2012 8:33:19 PM

maxalge said:
OK, now I see, it is a modular design power supply.

The box the power supply came with should have all the cables...


If it didn't then:


http://www.moddiy.com/products/OCZ-Modular-PSU-8%252dPi...


This is what you need?


did I read that company ships and is located in Hong Kong?

and if that PS only has 25amps worth of power a new one should be ordered.
December 29, 2012 10:25:22 PM

Best answer selected by Modestvolta.
December 29, 2012 10:27:18 PM

TX850 it is. And of course Newegg's price is so much better that ill have to wait a few extra days before I get it.

Thanks everybody!
!