Power hungry

By Alster37 · 22 replies
Feb 17, 2009
  1. hi!
    im gonna buy a 9800gtx+ black edition which runs at 785mhz. i have a 400watt psu
    and nvidia recommends a minimum of 450. i really dont want to replace the one i have. could i down clock to make the 9800gtx+ less power hungry?

    would there be any problems if i did?
    would my two standard fans keep it cool????

    thanks if you can help :D
  2. raybay

    raybay TS Evangelist Posts: 7,241   +10

    Sooner or later, you can expect problems unless you have a very high quality power supply. It is not the wattage that makes the difference. It is the quality of the build.
    For instance, an Antec is not good enough, but a PC Power and Cooling will handle it.
    But any power supply which provides power that dips and peaks under load may ruing your video graphics card... perhaps quickly... and will affect performance even if the video graphics card does not fail.
    Invest in a good 600 watt brand if you want to protect your investment, and need the performance.
  3. chrissof

    chrissof TS Member Posts: 59

    it`s not only the "watts" - but also the "amps"
    I just read a review yesterday,recommending a 550 watt psu and 30-32 amp`s on the 12 volt rail for the 9800gtx+ cards.
    and keep in mind that a high quality psu (80+ they are called) will even save you some money in the long term.power/energy consumption wise....
    a psu running on 100% all the time will die sooner,I think that is a fact
  4. raybay

    raybay TS Evangelist Posts: 7,241   +10

    A new set of views on power supply technology... Who calls them 80+... and how do they save you money.

    No power supply we have ever tested runs at 100% all the time... doubt it is even possible.

    References please.
  5. Alster37

    Alster37 TS Maniac Topic Starter Posts: 290

    i noticed about the power usage too. because my old pc used a 250watt psu and the graphics card recommended a minimum of 350watts but it still worked fine. so i was wondering if the wattage given with the psu is the maximum? does the pc change the wattage going in if the cpu and graphics card load increases? so could i stick with my psu but take it easy on the gaming until i get a new one and it would be fine?
    i used a power calculator software which claimed that my pc uses 251watts excluding graphics card. so gtx has 150watts of power to work with according to this.

    im confused help!!!!
  6. raybay

    raybay TS Evangelist Posts: 7,241   +10

    What is the brand of the 250 watt power supply, and the age.
    A wise person will always consider the power supply among the most important components that should not be compromised. Power supply calculators are worthless because there is no way to calculate what a poor quality PSU will do... If it is a top unit, you will be ok... but not great, with 250 watts... their cut-off at 350 watts is wise and likely correct... you risk the life of the 9800 GTX if you use the 250 watts...
  7. jobeard

    jobeard TS Ambassador Posts: 11,177   +990

    it is LOADED, not running and loaded to 100% of the design limit is called a 100% duty cycle.

    1) manufactures rate the equipment at ~90% of the true limit
    2) OEM installers plan on loading the device to about 80% duty cycle.

    to run at 100% duty cycle is to stress the device to its limits and will shorten the life of the device.

    Having build shortwave radio stuff, I usually set a duty cycle of 60%
  8. chrissof

    chrissof TS Member Posts: 59

    for all you guys out there interested in facts about psu`s check out the
    guru3d site (www.guru3d.com) here is a qoute:

    A PSU needs to manage the power demand in a very secure way otherwise it'll create instability throughout the system. That instability can result as crashes, freezes, underperforming software such as games that run poorly when the graphics card isn't fed enough power, and even resets or shuts down the system completely. Please do not underestimate the importance of the PSU.

    (taken from a review on an OCZ ModXtream PRO 600 psu on guru3d.com)
    I think that the guys at guru take the reviews very seriously and it is a trustworthy site to visit when planning on a new build or facing problems with your hardware.

    here is yet another qoute taken from that review:

    If you have a generic older power supply with an average 70% efficiency a 350 power draw (350/70x100) watt load would mean it is drawing 500 Watts of current from your wall socket while your PC only uses 350 watts, interesting eh? Yes, you loose 150 Watts yet are paying for that loss.

    Let's do that math again, yet this time with a 80% power efficiency in mind: 350/80x100= 438 Watt. So that's saving 64 Watts over a 70% efficient product. If you have your PC powered on a lot , think about this theory and what it can save you in the long term.

    Now if we estimate that today's tested PSU has a 85%-87% efficiency 350/85x100=412 Watt. We just saved 88 Watts by simply opting for a better power supply

    any questions,anybody? :)
  9. chrissof

    chrissof TS Member Posts: 59

    hi raybay
    I didn`t know I was that much "up to date" but with the upcoming "green IT" there have even been psu`s out there that are 85+ (and the companys are working on 90+) making them more efficient - simply meaning: to power up your pc they will draw less power and thus save you money.
    I`ve read reviews stating that a new (80+ and so on) psu will simply draw less power than lets say a 350 watt psu with an efficiency of only 65/70 when used in exactly the same rig.
    there are methods to measure that power consumption, I don`t know the english name for them...you plug them into your wall socket and plug your pc into that device and they show the power consumption.
    was that understandable?if not - shame on me,but I am german:wave:

    I just found the english name. boy ;i could have made that up myself: power supply tester

    edit again,damn I was wrong they are NOT power supply testers;probably rather called power draw meters,but I don`t know for sure
  10. Rage_3K_Moiz

    Rage_3K_Moiz Sith Lord Posts: 5,443   +38

    As raybay stated, it depends on what PSU you have and how old it is. Even if it is a quality unit from Enermax or Seasonic or any other good PSU manufacturer, if it is more than a year and a half old, you will need a new one.

    @chrissof, you are referring to the ubiquitous Kill-a-Watt meter. And FYI, I do not trust PSU reviews from any sites other than HardOCP, HardwareSecrets and JonnyGuru, since these guys test PSUs in the most thorough manner possible. Anyone with basic knowledge of how to deal with electric circuits can hook up a multimeter to a PSU, load it with two GTX 280s and measure the drop in voltage on the +12V rails. But the real issue comes when you conduct tests such as cross-loading, ripple and transient testing, as well as testing the PSU at different temperatures which simulates real case temperatures. This paints a far more accurate picture of the PSU's capabilities. Equally important are the components used, but to tell good ones from bad ones needs some experience in electronics.
  11. chrissof

    chrissof TS Member Posts: 59


    I do not trust PSU reviews from any sites other than HardOCP, HardwareSecrets and JonnyGuru

    hi rage,I`ve heard of hardOCP,good and reliable site for sure - and JonnyGuru sounds great to me,I will check out that site....
    and thanks for the name of that device,Kill-A-Watt,that puts a smile on my face....
    but please do check that guru3d.com site,it`s not all that "in depth" but I find the reviews there to be easy to understand and they never failed on me when planning
    on buying new hardware....and I am into tweaking and overclocking....
  12. Alster37

    Alster37 TS Maniac Topic Starter Posts: 290

    well my pc i got in november because i was upgrading and asking for advice. in the end i went for a barebones kit ( if you want a look i'll post the url) and used my 8600gt. it came with a 400watt psu and is fine. i bought it from novatech its a cheapish one. but in my old pc which had a 250 watt psu and a very cheap one. i was using the 8600gt which states on the box that it needs a minimum of 350watts.
    and i was overclocking and gaming with it until it melted through the floor. so why did it survive with such low power? I never revieved a warning of low power.

    and in the 9800gtx review on the techspot website it says that in idle the card consumes 141 watts of power and in stress(crysis) 100 more.

    so could my 9800gtx+ survive on 400watts if i cut down on the gaming?
  13. dustin_ds3000

    dustin_ds3000 TechSpot Chancellor Posts: 887   +19

    the 9800gtx+ black edition comes with a great warranty so if you burn out the video card you can easily get a new but if your psu goes then your mobo,cpu,ram could go too
  14. raybay

    raybay TS Evangelist Posts: 7,241   +10

    Getting any kind of a warning is Rare. In fact most of our repair customers do NOT report seeing one.
    You warning is the BSOD or the pauses or the noise or the odor... and the fact that you got a warning on the package reporting that you needed 350 watts...
    They have no way to warn against poor quality or poor power output... Power output is NOT detected. If so, the machine would probably shut itself down.
    Most components that you can buy for a computer have some sort of a warning or disclaimer on the package label or the product sheet inside the package.
    If there is one component that nonothings will try to save a few bucks, it is the power supply, but every other component depends on that power supply being good with an adequate reserve.
    Why don't users and builders and updaters buy the $65 power or the $88 supply instead of the $30... one of the mysteries of life,
    When enough computers or systems fail, the word gets around. Store clerks and online ads warn against inadequate power supplies, yet it doesn't seem to make any difference.
  15. Alster37

    Alster37 TS Maniac Topic Starter Posts: 290

    iv'e gone with a 550watt novatech psu. A very good and reliable company but this £19.99 psu will be a temp. As a month or so in i'l part with £58 and get a 550watt corsair or better. thanks for all the help :)
    ( and iv'e just become a member with 50 posts yay!)
  16. Alster37

    Alster37 TS Maniac Topic Starter Posts: 290

    I have been thinking about a 4870 instead. i was going for a £145 xfx 9800gtx+
    but for £25 more i could get a 4870 512mb sonic edition for £170 and ive decided to do so. but aparently it runs hot and is power hungry so will the original 550watt psu i was going to get enough or should i go for 600 or 650? and finally with the 2 fans it has attached to its case be enough to keep it cool?

    thanks for all your help guys :stickout:
  17. raybay

    raybay TS Evangelist Posts: 7,241   +10

    You will be fine with most 550 Watt power supplies, if they are not cheapos. There is hardly any difference between a 550 and a 650.
    Two case fans should be enough if actually in the wall of the case and not in a PCI slot.
    Any graphics card of that calibre will run hot... just keep the air moving out of the case.
  18. Rage_3K_Moiz

    Rage_3K_Moiz Sith Lord Posts: 5,443   +38

    The Novatech PSU cannot handle the new card. You would need the Corsair 550VX or OCZ StealthXStream 600SXS.
  19. Alster37

    Alster37 TS Maniac Topic Starter Posts: 290

    The corsiar is a bit expensive. I would class it as an expensive psu so is there like a middle class psu maybe thermaltake? im not sure. £35 maybe £40 would be my budget and i wuold like 550watts plus if you could find a psu with these specs i would be great.

    thanks :D
  20. raybay

    raybay TS Evangelist Posts: 7,241   +10

    Thermaltake will serve you just fine. I would avoid the similarly priced Antec as we have seen a lot of troubles with those over the past 7 months.
    You will likely be very happy with the Thermaltake, and it runs quietly as a bonus.
  21. Rage_3K_Moiz

    Rage_3K_Moiz Sith Lord Posts: 5,443   +38

    Thermaltake's ToughPower series is the only one worth buying from. Their other PSUs are mediocre at best, except if you are not going to game. And you simply cannot find a decent PSU for the HD 4870, for less than £60. I would suggest saving up and getting a quality PSU later, rather than getting a crappy one and putting your components at risk.

    Also, you may want to not consider getting an HD 4870, since unless you will be gaming at 1600x1200 or higher, an HD 4850\9800GTX+ will be more than sufficient for anything upto 1680x1050 with all image quality options maxed out. If you play at an even lower resolution like 1280x1024, then a 9600GT will do nicely.
  22. Alster37

    Alster37 TS Maniac Topic Starter Posts: 290

  23. Alster37

    Alster37 TS Maniac Topic Starter Posts: 290

    i have gone for a 9800gtx+ from asus which includes far cry 2 for £115
    the psu is uknown i will check the box and will buy a psu when i get the card.
    i will get a good one because its common sense :approve:

    join my thread later for the hunt for a gaming keybaord and mouse!
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