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can i run two 7950 on a 650w

Reptile Guy

Reptile Guy

Reptile Guy

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Will I be able to run two 7950's on a 650w psu,

My spec's

CPU, i5 3570k @ 4.1
mobo, z77x-3hd
ram, g skill ripjaw @ 1600hmz
ssd, samsung 840 120gb
HDD, 2tb seagate
PSU, Seasonic G series 650w '80 Plus Gold' Modular Power Supply
GPU, MSI Twin frozr III
 
spixelspixel said:
He has plenty of room for overclocking. Everything at stock in that pc will only use around 400w.
Click to expand...

At stock yes, but things start drawing a lot more power when overclocked

An overclocked 3570k can take an extra 100w
Overclocking the 2 7950's can take an extra 200w

I agree with Matt and would go easy on overclocking the 7950's if you only have a 650w.
 
If you check out the reviews and stuff for that PSU you cans see you can draw over 600W from the 12V rail alone. Its quite largely under rated.
 
imginy said:
At stock yes, but things start drawing a lot more power when overclocked

An overclocked 3570k can take an extra 100w
Overclocking the 2 7950's can take an extra 200w

I agree with Matt and would go easy on overclocking the 7950's if you only have a 650w.
Click to expand...

Theres no way an overclocked 3570k will take an extra 100w when thats the total it will use when overclocked a very decent amount.

Also an extra 100w per gpu is a bit unrealistic.
 
spixelspixel said:
Theres no way an overclocked 3570k will take an extra 100w when thats the total it will use when overclocked a very decent amount.

Also an extra 100w per gpu is a bit unrealistic.
Click to expand...

Check out any of the power consumption tests, cpu's and gpu's really drink the juice when you overclock.

3570k goes from the rig using 161w at stock to 267w when overclocked. That's an increase of 110w from a cpu overclock :eek:

http://www.bit-tech.net/hardware/cpus/2012/05/01/intel-core-i5-3570k-cpu-review/7

Check out any of the 7950 reviews where they compare power consumption on overclocked to stock and you will see just how much it increases.

Hardocp here has a single 7950 going from 395w stock to 529w overclocked.
That's a single 7950 taking an extra 130w when overclocked :eek:
http://www.hardocp.com/article/2013...lack_edition_video_card_review/9#.UWwMC8ojNOk

I could post you loads of examples of power consumption tests comparing overclocked to stock all showing same thing.
 
4.6Ghz 3570k
2x 7950s at 1000/1350 at 1.106v

Draws less than 500 watts on my system when I had my 620W PSU. Reading taken from a meter at the plug.

You will be absolutely fine.

EDIT: How the hell did you get 5Ghz on a 3570k on air? Impressive.
 
imginy said:
Check out any of the power consumption tests, cpu's and gpu's really drink the juice when you overclock.

3570k goes from the rig using 161w at stock to 267w when overclocked. That's an increase of 110w from a cpu overclock :eek:

http://www.bit-tech.net/hardware/cpus/2012/05/01/intel-core-i5-3570k-cpu-review/7

Check out any of the 7950 reviews where they compare power consumption on overclocked to stock and you will see just how much it increases.

Hardocp here has a single 7950 going from 395w stock to 529w overclocked.
That's a single 7950 taking an extra 130w when overclocked :eek:
http://www.hardocp.com/article/2013...lack_edition_video_card_review/9#.UWwMC8ojNOk

I could post you loads of examples of power consumption tests comparing overclocked to stock all showing same thing.
Click to expand...

There is too many contradictions between reviews so I just take them all with a grain of salt. That xfx card has a max possible power draw of 225w ( 2 x 6pin ) so I highly doubt those results unless its using 95w full load at stock? Here's a 3570k using under 100w at 4.8ghz with 1.33v http://www.overclock.net/content/type/61/id/1176265/width/500/height/1000/flags/LL
 
A stock HD7950b will hit 190w peak power cosumption, overclocked that number should surpass 200w, assume 100w for that CPU (thats a guess!) that leaves you plenty left over for drives/fans/etc and overhead.
 
Tobes said:
4.6Ghz 3570k
2x 7950s at 1000/1350 at 1.106v

Draws less than 500 watts on my system when I had my 620W PSU. Reading taken from a meter at the plug.

You will be absolutely fine.

EDIT: How the hell did you get 5Ghz on a 3570k on air? Impressive.
Click to expand...

I agree the rig would use around 400w at stock and around 500w with small overclock but on yours with the voltage at 1.1v the power usage is going to be a lot less than cards with 1.3v.

Tweektown have his same twin frozr 7950 card overclocked to 1185mhz in a bare minimum rig and it's drawing 502w and that's for a single card.
http://www.tweaktown.com/reviews/45...gb_overclocked_video_card_review/index17.html

I personally was drawing to much power with my single 7950/3570k for my 550w xfx core pro psu so have had to upgrade.
I do understand that his psu is better brand and that he probably isn't planning to push his cards as hard so he will probably be fine :)





As for my 5ghz I should change my sig really, I only use 5ghz for benchmarks then I just crank up the volts to around 1.55v.
http://www.3dmark.com/3dm11/5827971
4.7ghz at 1.35v is what I use the rest of the time.
 
Last edited:
I've got two overclocked 7950s and an i7 3770K and the max I've drawn from the wall ever (while gaming) is around 600W. More often that not it's hovering around 500W.
 
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