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Is my PSU bottlenecking my GPU?

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July 30, 2012 6:26:18 AM

Hey all, I'm new here, never even posted here and if this is in the wrong area I'm very sorry for that!


GPU - Radeon HD 7850 2 GB

CPU - AMD Phenom II X6 1055T Hex Core

RAM - 8 GB

OS - Windows 7 Ultimate 64-bit

Motherboard - Gigabyte GA-890GPA-UD3H (Socket M2)

I have two disk drives, one of which is a Pioneer Blu-ray drive.

PSU - 600W



Ever since getting my new Radeon HD 7850, I've noticed that I'm simply not getting the performance I should be getting out of it, and many people I've spoken to seem to tell me that my PSU is simply not powerful enough. I know my GPU recommends 500W, but apparently all these other components just take up too much wattage for the PSU to give enough power to the GPU. Is this true?

This is a sort of last opinion for me, I would love to get confirmation on this, because I'm pretty much ready to buy a new PSU once I get the 'go ahead'


Thanks!

EDIT: Forgot to mention, my PSU is about 6 years old!

More about : psu bottlenecking gpu

July 30, 2012 6:44:52 AM

I think it is causing a bottleneck. If the Radeon 7850 needs at least 500W and Newegg says your CPU needs 125W, then it seems to me that a 600W PSU isn't enough. I am not even counting the RAM, system fans, etc. So yeah you need a new power supply.
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a c 106 B Homebuilt system
July 30, 2012 6:47:10 AM

The 7850 is a very efficient card, much more so than any AMD or Nvidia card before, if you upgraded to it whatever was there before would have been drawing more.

600W should be sufficient to power that CPU and GPU. Only case I can think of is if the PSU has degraded significantly below its rated wattage and the previous card was low end enough that it didnt need it. Can we get more info on the PSU, if its a good brand this probably isn't the case but if its generic I would replace it on general principle.

Have you run any benchmarks on it yet? Getting an actual performance number and comparing it to what a review site is getting should tell you if there's a problem or if you just expected more from the card than it can provide.
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July 30, 2012 6:48:48 AM

I haven't really ran any benchmarks.. Do you recommend any in particular?
I also should mention that my PSU is about 6 years old, so I'm thinking that it's deteriorated quite a bit!
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a c 106 B Homebuilt system
July 30, 2012 7:00:29 AM

3D-Mark 11 is what I use to benchmark graphical performance. Though it does also incorporate the CPU and RAM in the test, so try to compare to similar systems.
http://www.3dmark.com/3dmark11/download/

Furmark is also another if you want to stress it to the max to make sure its stable and to see what its max temp is. If the cards getting insufficient power, there should be artefacts all over the place or it will just fail outright.
http://www.ozone3d.net/benchmarks/fur/

If your PSU is that old, I would say replace it regardless. Nowadays you can get a much more efficient unit.

Well there's your problem. The 12v rail only has 29amps on it. So it can only provide 348W to both the CPU and GPU. I am fairly sure that's insufficient (and its a generic, so we cant even be assured whats on the sticker is actually happening).

So I guess the biggest question is, whats your budget for a new PSU?
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July 30, 2012 7:03:00 AM

Oh man it feels really good to finally get a good diagnosis, lol.
As for budget, I think my max would be around $250
Do you have a recommended PSU wattage search for?
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a c 106 B Homebuilt system
July 30, 2012 7:15:19 AM

On a single card AMD build (I add another 50W onto the usual recommendation because AMD chips tend to have a higher draw), I recommend 650W. That will give you room to overclock the components and add a decent number of drives. If adding another card in SLI/Crossfire is a possibility, an 800W supply is what you need.

$250 is plenty for a PSU, you can spend a lot less and still get good quality.

These are about the best you can get, Seasonic is an amazing brand and Gold efficiency is as high as you can get without going 1000+ Watts.

Seasonic X650 Gold, fully modular. $140
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Believe it or not, but none of the good names in PSU's make 800W supply's, only 750's and 850's. The Seasonic Gold 850W costs the same amount as this one, so why not upgrade 200W? It may be an issue if you don't have a lot of room in the case. Competing brand Gold 850W PSU's also cost around the same amount.

Seasonic 1050W Gold Fully modular. $200
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
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July 30, 2012 7:17:49 AM

Best answer selected by Azurex.
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July 30, 2012 7:18:38 AM

Thank you very much for all this!
I definitely appreciate it~
Gonna look into a Seasonic one most likely!
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a c 82 B Homebuilt system
July 30, 2012 7:19:48 AM

AMD recommends a 450w power supply for a SYSTEM with a single HD 7850.

http://www.realhardtechx.com/index_archivos/Page362.htm

This assumes you have a generic, junk brand power supply. And you have one. That so called 600w model supplies 29 amps on the 12v rail for 348 watts on the 12v rail. A quality new model would label that a 380-400w unit.

As said above the unit may have degraded ( all power supplies suffer capacitor aging ) over time and it did not start life as anything decent.

It is very likely not the power supply causing your problems. That said I would replace it ASAP and I would give you that advice even if the unit was new. Models like that are the kind that go "bang" and destroy your motherboard and graphics cards when they die.

Anypower supply of 450 watts and up from Corsair, Seasonic, PC Power and Cooling, XFX, Silverstone, Enermax, OCZ or Antec will do.

Do you have all the latest drivers?

Quote:
I think it is causing a bottleneck. If the Radeon 7850 needs at least 500W and Newegg says your CPU needs 125W, then it seems to me that a 600W PSU isn't enough. I am not even counting the RAM, system fans, etc. So yeah you need a new power supply.


Anytime you see a recommended power supply size based on a card it includes the whole system. Not understanding that is why people have 1000w power supplies with their HD 6850s.
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a c 82 B Homebuilt system
July 30, 2012 7:24:02 AM

manofchalk said:
On a single card AMD build (I add another 50W onto the usual recommendation because AMD chips tend to have a higher draw), I recommend 650W. That will give you room to overclock the components and add a decent number of drives. If adding another card in SLI/Crossfire is a possibility, an 800W supply is what you need.

$250 is plenty for a PSU, you can spend a lot less and still get good quality.

These are about the best you can get, Seasonic is an amazing brand and Gold efficiency is as high as you can get without going 1000+ Watts.

Seasonic X650 Gold, fully modular. $140
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Believe it or not, but none of the good names in PSU's make 800W supply's, only 750's and 850's. The Seasonic Gold 850W costs the same amount as this one, so why not upgrade 200W? It may be an issue if you don't have a lot of room in the case. Competing brand Gold 850W PSU's also cost around the same amount.

Seasonic 1050W Gold Fully modular. $200
http://www.newegg.com/Product/Product.aspx?Item=N82E168...



This recommendation is insane. Completely overdone for what you are running. Any 450w and up unit from the brands I recommended will power your system even overclocking everything as far as it will go.

It's even overkill if he adds a second card.
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a c 106 B Homebuilt system
July 30, 2012 7:38:03 AM

Its completely justified. This 500W supply from XFX (so I'm not being unfair and pointing to a bad unit and its on your recommended brand list) has a 12v rail at 39A, so 408W max draw from the 12v rail. The CPU has a draw of 125W (which can be made higher through overclocking), so that leaves 283W for the GPU.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

According to this review of the Gigabyte 7850, it can draw up to 279W (overclocked). So you have 4W left over, which is cutting it fairly fine don't you think?.
http://www.vortez.net/articles_pages/gigabyte_hd7850_oc...


Just realized that was total power draw at the wall, not the individual card. This review estimates a non overclocked 7850 at full load will draw ~106W, leaving 177W left over. I'l admit I was wrong here. But in my opinion, nothing wrong with an overkill PSU.
http://www.guru3d.com/article/amd-radeon-hd-7850-and-78...

And I recommended the 1050W supply because its the same price as the 850W (Which I recommended because there aren't any 800W's) with the same features, so why not?
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a c 82 B Homebuilt system
July 30, 2012 7:56:38 AM

You recommended a 650 and 1050w Seasonic X series power supply for a single HD 7850 system.........and that's not insane?

Might as well convince people they need to piss away $150 for a mid level computer power supply. When in reality a good quality 450-500w model can be had for ~$50-$65.

Nice edit BTW. And in fact you did not recommend the XFX or Silverstone anywhere I see.
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a c 106 B Homebuilt system
July 30, 2012 8:03:43 AM

Accidentally didn't include the link to it when I first posted, its there now.
Got rid of the Silverstone after I realized I was in the wrong, And I explained my reasoning for the 1050W.
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a c 82 B Homebuilt system
July 30, 2012 8:14:32 AM

Before you recommend something like a $150 Seasonic X series at least make sure the person needs it. This guy does not and as such should be told that. If he wants double to triple the power he needs at 2 to 5 times the cost as with your recommendations he needs to know that there is no reason to spend that money when he can get a good quality unit for less than $60 that will do him fine.
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November 29, 2012 9:05:49 AM

I have the same issue i just bought a HD 7850 2GB and did some bench-making using unigine Heaven DX11 Benchmark

I got 23 fps and score of 580 (very low compared to reviews benchmarks), i saw on other ppl using same setting getting 45 fps in unigine Heaven

My PC:
CPU : AMD Phenom II X6 1055T 2.80/3.30 GHz
Motherboard : ASRock 880G Extreme3
PSU: Sirtec 400W http://www.highpower-tech.com/eng/product_page.php?clas...
Memory: 12 GB


@ Azurex Did u solved your problem?
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November 29, 2012 11:22:04 AM

Yes! I did.

My problem was that the graphics card wasn't seated properly... Which essentially means that I had to pull it out of the slot, and put it back in, and pretty much that fixed it! It was really as simple as that.


Btw, if that doesn't fix it, I'd probably recommend getting a new power supply, as 400W is fairly weak. Also make sure you have the latest drivers on your machine, and be sure that there are no unneeded processes running in the background whilst performing a Benchmark test or playing a game!
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