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R9 270 on a 430W PSU?

Discussion in 'Graphics Cards' started by Cal_G, 5 Feb 2014.

  1. Cal_G

    Gangster

    Joined: 29 Feb 2004

    Posts: 345

    Location: Netherton Ghetto

    Would the above work okay? The machine currently has an old x1800xt which also requires 1x 6 pin PCI-E connector and that is still running flawlessly since the card came out!

    The plan is to buy the card now (MSI Radeon R9 270 Gaming 2G AMD Graphics Card - 2GB), then in a couple of months replace the board, CPU and RAM to a mid range AMD setup, maybe a 6 core and 8GB of memory.

    Is this plausible with keeping everything else as it is?

    Many Thanks.
     
  2. MeatLoaf

    Capodecina

    Joined: 1 Dec 2005

    Posts: 14,055

    Location: Stoke on Trent

    Depends what make the PSU is really :)
     
  3. andy_mk3

    Capodecina

    Joined: 5 Oct 2009

    Posts: 11,288

    Location: Lincolnshire

    As long as it's a good brand it will be fine.
     
  4. Noxvayl

    Gangster

    Joined: 27 Jan 2014

    Posts: 121

    Location: Waterlooville

    What PSU do you have?

    You'll need something that is rated for at least 25A on the 12V rail, 30A would be a lot better.

    You can work it out based on the Thermal Design Power (TDP) devided by the 12V it is supplied with to get the amount of amps required to provide the power you have. I always add at least 100W for the CPU and then a few extra Amps for Hard Drives and fans in the case just to be safe. The equation is Power (Watts) = Voltage (V) x Current (I, Amps).
     
    Last edited: 5 Feb 2014
  5. Cal_G

    Gangster

    Joined: 29 Feb 2004

    Posts: 345

    Location: Netherton Ghetto

    Should have mentioned the make, sorry about that!

    It's a Seasonic, was expensive back in the day but never had a single problem with it. I've got a photograph of the sticker somewhere so will have a look.

    Thanks for the replies.
     
  6. Cal_G

    Gangster

    Joined: 29 Feb 2004

    Posts: 345

    Location: Netherton Ghetto

  7. synixx

    Wise Guy

    Joined: 4 Nov 2007

    Posts: 2,352

    Location: Scotland

    Seasonic are a great brand but personally given the age of the PSU I would avoid running anything power hungry on that.
     
  8. spixelspixel

    Wise Guy

    Joined: 10 Jan 2012

    Posts: 2,379

    Last edited: 6 Feb 2014
  9. Cal_G

    Gangster

    Joined: 29 Feb 2004

    Posts: 345

    Location: Netherton Ghetto

    I've been using a molex to 6 Pin since the machine was built. Always been rock solid so figured it should still be okay to use. From what I can see the x1800xt is a power hungry card, or at least was when it was released.

    The rest of the system is basic, 1x HDD, 1x SSD, optical drive and a couple of case fans.
     
  10. spixelspixel

    Wise Guy

    Joined: 10 Jan 2012

    Posts: 2,379

    I believe the x1800xt uses about 100w while the 270 will be closer to 150w.

    It will probably still work fine but I have a thing against using adapters :) For 40 pounds I'd definitely recommend upgrading the psu just to be safe. Also, it has 2 x 12v rails but you don't know how they're split. The one you're using to power the gpu might also be powering the cpu, if that's the case there will be some trouble as both rails are under 180w each.
     
  11. Noxvayl

    Gangster

    Joined: 27 Jan 2014

    Posts: 121

    Location: Waterlooville

    That PSU will be fine, even accounting for capacitor ageing you still have power spare with it. The PSU takes care of splitting the rails dynamically so if more power is needed and one rail is at full load the power requested will be delivered via the spare rail. There is no need to spend money on another PSU when your current one is fine.
     
  12. spixelspixel

    Wise Guy

    Joined: 10 Jan 2012

    Posts: 2,379

    Where did you get this info?

    The only difference between a single and multi rail psu is the 'rail' limitations so this makes no sense. Pretty sure each one is given its limit (as per the spec), if its exceeded the psu's OCP will kick in and shut it off. Example of a psu which lists how the rails are split

    http://images.anandtech.com/doci/5758/leist.PNG
     
    Last edited: 6 Feb 2014
  13. Noxvayl

    Gangster

    Joined: 27 Jan 2014

    Posts: 121

    Location: Waterlooville

    The power being delivered by the PSU will be higher than the rating for the individual rails because the PSU only produces one source of 12V for the computer, it just delivers that 12V over multiple rails because it is safer to do so. Multiple rails carrying less current each are cooler than a single rail carrying the full current so there is less risk of burning out the rail at high loads.

    The power law equation is my guide for how much power the PSU can deliver (P = I * V, P = Watts, I = Amps, V = Volts). The one you posted is rated at 492W on the 12V rails and as such it can only deliver that power when using a current of 41A.

    If you'd like to read more about Single vs Multiple rail PSU check these posts out:
    http://www.jonnyguru.com/forums/showthread.php?t=3990
    http://www.overclock.net/t/761202/single-rail-vs-multi-rail-explained

    I couldn't find the review I read that took apart a PSU and showed where the 12V rail is and how it is split. It doesn't act as two separate rails giving power to different parts of the computer, it is one rail that is converted into 2 to transfer power from one side of the PSU to the other safely; there is only one origin point and the rails come together at one end point; they act as a parallel circuit splitting the current between them.
     
    Last edited: 6 Feb 2014
  14. Cal_G

    Gangster

    Joined: 29 Feb 2004

    Posts: 345

    Location: Netherton Ghetto

    Thanks for the input fellas. I'm willing to give it a go. The question now is, is a 125W AMD chip out of the question or should I stick to 95W.
     
  15. spixelspixel

    Wise Guy

    Joined: 10 Jan 2012

    Posts: 2,379

    This doesn't really explain anything to be honest. In fact both links you posted imply the load is not distributed among the rails, instead each powers a certain component like in the screenshot I posted above.

     
  16. Cal_G

    Gangster

    Joined: 29 Feb 2004

    Posts: 345

    Location: Netherton Ghetto

    Quick update. Will be able to get hold of a barely used 500W, namely this one:

    http://www.silentpcreview.com/article241-page2.html

    The review suggests one 12V is used exclusively for the CPU and the other for the rest of the system. Even if it is the case of it being split, there should still be plenty of breathing room to run the R9 270 and an FX 8320 (overclocked) from the looks of it.
     
  17. Noxvayl

    Gangster

    Joined: 27 Jan 2014

    Posts: 121

    Location: Waterlooville

    It seems you are right. I can only find the bequiet! Dark Power Pro power supplies with a switch that changes the system from 4 rails to single. I must of assumed from this functionality that it was common to have the rails done in parallel.

    I can't find any reference to rails powering separate bits for Enermax PSUs that I use either which would of confirmed my assumption when I initially made it.

    Your current PSU will be fine. If you would rather be safe then sorry then I wouldn't get another old PSU, you'd be better off getting a new one.

    SuperFlower Golden Green HX 450W - £54

    or

    Seasonic G Series 450W - £65

    The above options would be my short list for a power supply to run your system. Both are gold rated, 5 year warranties and are manufactured in house rather than using an outside manufacturers design.
     
  18. Cal_G

    Gangster

    Joined: 29 Feb 2004

    Posts: 345

    Location: Netherton Ghetto

    Everything I need to replace keeps bumping the price up more and more.
    I fully agree that a high quality PSU is essential. The 500W I linked to above has been used far less than my own and well taken care of. Seems a better idea to go with that one.

    Thanks for the reply.