Upgrade to 4850, but power supply issues

Hey people, I'm new around here and I was hoping someone might be able to help me out.

I just bought a new computer, specs are:

2.53Ghz Core 2 Duo E7200
4096MB DDR2 Interleaved RAM
250GB SATAII Hard Disk 7200rpm
Elitegroup 945GCT-M2/1333 Motherboard; 1333 Mhz FSB
Inno3D GeForce 8600GT 256MB DDR3
Windows Vista Home Premium
450 watts PSU

I think I'm not too satisfied with the graphics card, and as the title says I am intending to upgrade to a 4850 but will a mere 450 watt PSU be able to handle the load? How do I calculate the power required by all the rest of the individual components?

Please help me out, I'd really appreciate it.
21 answers Last reply
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  1. it depends what kind of psu is it....

    was it cheap...? then I doubt it.

    If you don't want to spend alot of money on PSU
    try buying some cheaper but with say.. 550 watt
    or so...

    btw check at where you wanna get that PSU
    the prices of given PSU's and come back here.
  2. it all depends on the brand/quality of your psu. the 4850 requires a minimum of 450 watts, so if you're using a psu that came with your case or cost $10, then you definitely need a new one.
  3. How many amps does 12v have? If it has at least 30 you should be fine, unless you're doing something extra that you didn't label because I calculated your power usage (even put some overclock on cpu if you ever want to do that) and it came out 312 watts. That 450 watt minimum they have labeled on that card is more safety precaution so that consumers actually check their psu's.
  4. foxhound009 said:

    If you don't want to spend alot of money on PSU
    try buying some cheaper but with say.. 550 watt
    or so...


    This is not a very good reccomendation
    Check the specs of these cheap psu's

    http://www.newegg.com/Product/Product.aspx?Item=N82E16817184008

    http://www.newegg.com/Product/Product.aspx?Item=N82E16817707015

    Notice how the +12v output remains the same (22a), even though one is 450 watts and the other 550 watts.
  5. Corsair TX450W is a good PSU for the HD4850 at a decent price from Newegg.

    If you plan on OC or going CF get a decent 650W+ lke Corsair TX650W.
  6. Thanks for the quick replies!

    Might I ask, by the way, how does the 12V output affect your computer?
    And also how do I calculate the number of amps I have on a 12V?
    I also read something about 12V rails or something like that, what's all these stuff?

    Forgive me, I'm a little muddled when there're so many things I have to consider.
  7. A "single RAIL" rated at least 31 AMPS is what I remember is what ATI recommends for the 4850. So when you buy a PSU check out the specs and make sure it can handle that.

    The Corsair TX450W can handle it. Most quality PSU will include specs like "single RAIL".
  8. According to some reviews/tests the 4850 draws roughly 275W of power when fully loaded. That means it needs (roughly) 23A.

    Of course, that is at stock speeds. So it's probably more like 25A+ if you are overclocking it.
  9. ^^I think this is what qwanvbva is referring to
    http://www.theinquirer.net/gb/inquirer/news/2008/06/26/close-look-ati-4850-4870

    267W is for the ENTIRE system. They did some math and came up with a 134W for the card itself, which is more plausible since the card has one 6 pin pcie power connector that can supply around 75W and the slot itself another 75W...

    and those manuf recommendations are overly cautious anyways, I'd say the OP will be just fine with his current PSU, anyways invest into a kill-a-watt type consumption meter (like $20 or something) and measure what your usage is with the new card, if it gets say over 75% of the rated wattage then it might be a good idea to get a bigger psu (and thats not taking into account the effiency of the PSU, it'll draw more from the wall than the components actually use)
  10. As I stated in the other thread. I did misread the table but I have also seen two other reviews that state a 4850 uses roughly 250W and a 4870 275W+.

    One of them also compared the power draw to other major cards.

    Perhaps I misunderstood the others.

    I'll see if I can dig those up as well and verify it.
  11. doublepost
  12. After going back and reading a half dozen or so reviews again. Some state total system power and some only mention the numbers as "the cards power consumption".

    A couple have actually added notes that the power consumption is for total system power.
  13. SonDa5 said:
    A "single RAIL" rated at least 31 AMPS is what I remember is what ATI recommends for the 4850. So when you buy a PSU check out the specs and make sure it can handle that.

    The Corsair TX450W can handle it. Most quality PSU will include specs like "single RAIL".


    After going back and reading more... This is inaccurate. ATI recommends at least 31A on the 12V rails (total).
  14. BTW, I feel 134W is dangerously close to the 150W maximum draw (75W from PCI-E bus and 75W from the PCI-E connector) since these are at stock settings. I would be curious to see if anyone has tested the power draw when they are overclocked.

    Then again, they say to take off ~20% due to the PSU's inefficiency. So that probably makes for any added power requirements from overclocking.
  15. I also posted some more information in a related post.

    http://www.tomshardware.com/forum/253548-33-underperforming-4850s#t1851636
  16. gmanvbva said:
    BTW, I feel 134W is dangerously close to the 150W maximum draw (75W from PCI-E bus and 75W from the PCI-E connector) since these are at stock settings. I would be curious to see if anyone has tested the power draw when they are overclocked.

    Then again, they say to take off ~20% due to the PSU's inefficiency. So that probably makes for any added power requirements from overclocking.


    Think about this, if there was even a chance of the card drawing more power than can be provided by the combination of the slot and the external power connector ATI would have added another power port.
    If it will help you to feel better , tests have shown that the 4850 under max load only draws 110 watts
    http://www.xbitlabs.com/misc/picture/?src=/images/video/ati-radeon-hd4850/hd4850_power_full.png&1=1
  17. Was there a article related to that picture?

    Preliminary spec released prior to the release of the 4XXX state the power draw with load to be 120W. So it all seems to be in the right ball park.


    http://translate.google.com/translate?u=http%3A%2F%2Fwww.hartware.de%2Fnews_44085.html&hl=en&ie=UTF8&sl=de&tl=en
  18. Thanks. I had started reading that article earlier but didn't make it to page 14 yet.
  19. It should run it if it's a good enough quality PSU. I ran my HD 3870 on an FSP AX450 watt power supply, and I never had any issues with it. The 4850 isn't that much more power...

    Just make sure your power supply has a 6 pin PCIe power connector (looks like this http://www.worldofstock.com/closeups/BTE1741.php ) . Some brands come bundled with a molex to pcie connector if your psu dosen't have one (my Visiontek 4850 did, as do Gigabyte and Sapphire).

    You can always try, and if it doesn't work get a new PSU.
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