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Would you trust a Corsair HX750 to OC this rig?

Discussion in 'Overclocking & Cooling' started by BigMack70, Apr 6, 2012.

  1. BigMack70

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    Hi all,
    I am upgrading my rig to the following:

    ASrock Z68 Extreme7 gen3 mobo
    Core i7-2600k CPU
    Noctua NH-D14
    2x4GB of DDR3-1333 ram
    2x 7970 in CF (XFX DD BE + MSI Lightning)

    I have two hard drives, no optical drive, 6 case fans, and about 10 USB devices attached.

    My power supply is an HX750 at the moment, which I have been very happy with. However, would you trust it to deliver enough power to this rig once overclocked? I know that it is plenty to handle everything at stock, but I plan to run the 7970s at 1200 MHz core and the 2600k at as close to 5 GHz as I can get it.

    My XFX 7970 requires 1.225V on the core to run at 1200 MHz, the lightning hasn't been installed yet but I assume that it will be similar.

    Do I need to upgrade my PSU? I'm thinking that it might be able to handle everything but am just not sure. Really don't want to upgrade if I don't have to. If you think I do need an upgrade, what do you think of the Corsair AX-1200 as an option?

    Thanks!
     
  2. entropy13

    entropy13

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    The HX750 is barely enough as it is, while the AX1200 may be too much for your needs. The AX850 would be enough. Or try the Seasonic X-1050.
     
  3. Aquinus

    Aquinus Resident Wat-man

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    I'm not sure, if you have a kill-a-watt to find out how much you're drawing at full load, you could be smart about it but 750-watt seems a bit small. Just overclocking my 3820 and leaving my 6870s at stock I draw about 550 watts, I could see 650 if I overclock the 6870s, but the 7970s draw much more than the 6870, so I would be careful at full power. I got a 1kW Seasonic just to make sure that I would have enough overhead without needing to worry about it.

    I'm seeing other 2600k + 2x7970s drawing 650-watts alone, if that is the case you might want to consider something bigger. Also keep in mind that closer to maximum you run a PSU the hotter it will get.

    I'm using this and I'm very happy with it. Even at full load it doesn't make a whole lot of heat: SeaSonic Platinum-1000 1000W ATX12V / EPS12V 80 PL...

    Edit: I might also add that it is 80 Plus Platinum, so the power draw off the wall will be lower with this PSU versus an 80 Gold or lesser PSU with the same hardware, not that 4-6% makes much of a difference, but >10% could on your power bill if your rig runs 24/7.
     
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  4. BigMack70

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    Yeah... I know that 750W isn't enough, but is 850-900W enough? Most reviews of the HX750 suggest that it can put out between 850-950W reliably.

    Thanks for the thoughts!
     
  5. radrok

    radrok

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    Bear in mind that with time PSUs tend to lose power output so if you plan to keep this rig for more than 2 years then I'd say you should pick a bigger PSU.
     
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  6. Outback Bronze

    Outback Bronze

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    Well if u dont want to bust any of your components i wouldnt. Look 4 a decent 1000+. Nice rig btw.
     
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  7. BigMack70

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    Thanks guys... I've gotten advice both ways, which pretty much confirms for me that I might be OK but I'm putting the HX750 on the borderline of what's a good idea.

    I think I will just bite the budget bullet and upgrade to an AX1200. I know it's overkill, but I've had bad experiences in the past when I tried to skimp on my power supply and once this rig is built I dont want to have to replace anything for at LEAST 2 years.

    Anyone interested in buying my HX750 for ~$100+ ? Probably will put it up on ebay next Tuesday (on vacation until then).
     
  8. Kreij

    Kreij Senior Monkey Moderator Staff Member

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    Also keep in mind the efficiency of the PSU. The hx750 (80+ silver) runs at max efficiency somewhere around 325 watts and starts to drop off at about 370. The ax1200's (80+ gold) sweet spot is at 600watts.
    If efficiency is a concern the 1200 is a far superior PSU for what your rig is likely to draw, plus you would have headroom to add more without efficiency taking a nose dive.

    If you want to sell your 750, please use the BST section and follow the rules, not this thread. Thanks.
     
  9. entropy13

    entropy13

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    The XFX Pro 1250W, Seasonic X-1250W, Kingwin Lazer Gold 1200W, Rosewill Lightning 1300W, are all cheaper alternatives but are just as great as the Corsair AX1200.
     
  10. BigMack70

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    Sorry, didn't mean to try to turn this into a "FS" thread. If anyone is interested, I have a thread over on tomshardware's deals forum for it. I don't think I look legit enough here to sell anything, since I'm new to these forums.

    Thanks again for all the advice about the PSU, guys! My wallet is stinging a little bit (well.... it was already with 2 7970s), but I can just work some extra hours this next month to help pay for it all :)
     
  11. JrRacinFan

    JrRacinFan Served 5k and counting ...

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    Yes, you can either:

    a) Lower your gaming res and run VSYNC, this should pull the peak power down some.

    b) Purchase your new PSU, continue to save for that second card so to make you essentially Crossfire ready.
     
  12. Kreij

    Kreij Senior Monkey Moderator Staff Member

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    People are usually more interested in your heatware rating than your post count.
    Plus, the only way to get known as a good TPU seller is to start selling stuff (and be a good seller, of course. :D)
     
  13. BigMack70

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    I ordered the upgrades while on vacation this week... already have everything sitting at home waiting for me (new case, new CPU+mobo, 2nd 7970)

    Just put in the AX1200 order from Amazon, will be there on Monday waiting for me when I get home :)

    Now just have to earn some extra cash so that my bank account stops crying.
     
  14. theoneandonlymrk

    theoneandonlymrk

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    ive just upped from an 850TX to a 1200AX ,youll not be sorry though i do have to say modular is apparently balls, it takes up more space not less and i ended up saving on only 2 wires not connected , ah well , less crashes now:)

    you want to be in the mid to low third of a PSU's max output for max efficiency ,if your their at idle then that will do:)
     
  15. qubit

    qubit Overclocked quantum bit

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    You're right to suspect you need a bigger PSU, as the others have been saying. When buying, I recommend going a bit overboard with it and getting 1000w+, as you then won't have any power worries for a long time.

    Look at my rig: it's got a Corsair HX 850 and it's never really stretched all that much. What do I get in return? Peace of mind, clean stable power from a quality supply, low noise and reliable operation.

    There are arguments about not getting the best efficiency from an overpowered PSU being run with a light load, but I think that small point pales into insignificance compared to the other benefits.
     
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  16. BigMack70

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    I've been persuaded to the point where I agree completely with this. Also, given all the money I've dumped into this rig in the past couple months (~$2k), I'd rather not have to touch anything in it for a few years (except maybe adding a 480gb+ SSD once they get cheap), and I figure a super high quality overkill PSU is part of getting to that point.
     
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  17. Kreij

    Kreij Senior Monkey Moderator Staff Member

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    BigMack, if you have a moment go into the UserCP and enter your system specs so people can easily see them and you don't have to type them everytime. Don't forget to check the box that allows us to see the specs you enter. :)
     
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  18. BigMack70

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    Done and done.

    Will update everything next week after I get the new build together.
     
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  19. JrRacinFan

    JrRacinFan Served 5k and counting ...

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    :ohwell: I hear you on that one. I'm waiting on my SSD & a board to base my upgrade off of. Waiting waiting waiting, and yet I still have to sell/trade off a few things. Patience, that's all you need right now.

    Thing of it is, to where I've been saying this for a while now, do you actually NEED tons of power if all you're doing is surfing the web and gaming at 1680x1050 or **insert lower than 1080p here**. I know I like overkill but how much further past overkill is really required? Not discrediting your build, I love it. It should last you quite a few years to come. :toast:
     
  20. BigMack70

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    I've just had bad experiences with skimping on PSUs in the past... it's left a bad taste in my mouth.

    Same thing with motherboards... I've seen one too many VRMs explode.

    It's cheaper to pay for overkill the first time than it is to replace parts that just didn't quite cut it in the long haul.
     
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  21. JrRacinFan

    JrRacinFan Served 5k and counting ...

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    Yup! Totally agreed, here's a little something to take a peak at:
    http://www.techpowerup.com/reviews/AMD/HD_7970/26.html

    Average is ~160W with Peak Max @ ~270W. If you vsync, odds are it will be near the average power or a smidgen less. So looking at ~400W(overestimation) in cards alone, for 80+ efficiency JUST IN CARDS alone you will need an 800W as most power supplies are USUALLY most efficient at 20%, 50% and 90%(I don't recommend this) loaded to them. So you were steered the right way, the AX1200 is a beast of a psu and will keep you up and running for a LONG time coming.
     
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  22. Kreij

    Kreij Senior Monkey Moderator Staff Member

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    I agree with you Mack, a bit more money upfront usually means less problems down the road.
    I've had zero problems with my rig (other than an occasional DOA RAM stick) and my trusty old TT TP 750 has happily taken anything I've throw at it and it's years old.

    Here on TPU, the term "overkill" has no meaning for most. :laugh:
     
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  23. Yukikaze

    Yukikaze

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    I am running the rig in my specs on a TX750, FWIW.
     
  24. BigMack70

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    Yeah, I'm thinking that it would have worked OK for now... I'm more worried about how it would be doing in a couple years.

    Once I get the rig overclocked to my liking, I don't plan on touching it for a longggg time except for really minor stuff. Worried that the PSU wouldn't be able to handle being put under that much stress for much longer than a year.

    It was a nice overkill PSU for a single GPU rig, and now I'll have a nice overkill PSU for a dual-GPU rig :D
     
  25. theoneandonlymrk

    theoneandonlymrk

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    it will do 3x gfx cards too;):D(ax1200) i only bought it because i want to throw a decent nvidia card in for physx and a gt240(low power no psu plug) wont cut it anymore im holding off on a 560 as they will be cheap as chips soon or as abundant second hand as apples in my back yard soon
     

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