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GTX 260 and power

By alisbin
Oct 7, 2008
  1. hey all,
    i'm building a new comp and i'm considering a gtx 260 but i havn't figured out the real power requirements. i'm not getting SLi to start with but i will be upgrading to it in 6 months.
    so, what wattage do i need in a power supply and what amperage along the 12v rail do i need, i've seen some PSs with 40a+ on the 12v but they only have 1, do i need more? all the PSs that i've seen with multiple 12v rails seem to have around 18a max.

    what i'm planning on running: 1 7200 system HD, 1 or 2 5400 storage drives, 2 gtx 260s, 1 sound card (turtle beach probably not sure yet), 1 wi-fi card, E8500 (wolfdale) core 2 duo, DDR 3 ram (4 gig, 2 sticks, pc 1600), 1 DVD/r, 3-4 case fans. not sure which mobo yet but probably whatever EVGA board that can handle the DDR3. not planning on any case mods that use power and i have an IPS for consistant incoming power.
     
  2. EXCellR8

    EXCellR8 The Conservative Posts: 1,835

    You're gonna need some generous power to run such a setup, I would recommend at least 750-800w+ if you're looking to add another 260. PC Power & Cooling "Silencer" 750 power supplies are really good units; should be enough to power two cards along with all the other stuff without a problem. I believe they have four +12v rails but I might be thinking of something else, will need to double check on that one.
     
  3. alisbin

    alisbin TS Rookie Topic Starter Posts: 93

    the PS mentioned has 1 12v rail at 60a. that sounds fine as long as i don't need more rails, do i?
     
  4. Rage_3K_Moiz

    Rage_3K_Moiz Sith Lord Posts: 5,431   +28

    SIngle or multiple rails don't matter, the total combined current on the +12V rails does. For your proposed setup, both cards together will pull around 360W, which is 30A from the +12V rails alone. So taking into account your other parts, get a PSU with at least 60-65A on the +12V rails. I recommend the BFG ES-800 and the Thermaltake ToughPower 850W as excellent choices.
     
  5. alisbin

    alisbin TS Rookie Topic Starter Posts: 93

    ah ok that makes sense, is there any benefit to 1 big rail vs multiple small rails?
     
  6. Rage_3K_Moiz

    Rage_3K_Moiz Sith Lord Posts: 5,431   +28

    Not really no, since multi-rail PSUs with 18-20A on each +12V rail usually reserve separate rails for each PCI-E connector, so each card is on a separate +12V rail that can deliver 18-20A of current, which is roughly 200-240W of power, far more than what the GTX 260 consumes, (around 190W. Be aware that the PCI-E slot also provides 75W of power, so the card needs far less than 190W from the +12V rail). Multi-rail PSUs may provide a better scenario where each card is on a separate rail, so it doesn't draw power from the same rail powering the CPU, HDDs etc. In single-rail PSUs, all components draw power from a single large rail. But in both cases, assuming the PSU has a combined +12V current rating of >65A, it will be impossible for either card to draw so much power that it overloads that particular rail (in case of a multi-rail PSU) or the entire +12V rail (in single-rail PSUs).

    So don't worry, it won't make any difference in performance or stability.
     
  7. alisbin

    alisbin TS Rookie Topic Starter Posts: 93

    awesome, thanks for the info
     
  8. alisbin

    alisbin TS Rookie Topic Starter Posts: 93

    ok, making my final PS decision and i realized there was one thing i hadn't thought of asking.
    first of all, kinda oscillating between the PC Power & Cooling S75QB 750W (1 60a 12v rail), the thermaltake toughpower 850 and a muskin 800. so, one thing i still don't quite get about rails and power, if i have multiple rails does that mean multiple connectors that i have to keep track of? or is it purely internal to the PS, and also, the mushkin has 3 rails at 20 and rail at 26 vs the toughpowers, 2 at 30, 2 at 18. but the thermal take is about $100 more, is it worth that?
    (checked out that BFG, but alot of newegg reviews were poor on it, lotsa RMAs neede, price is nice for promised power though).
    my power supply died this morning so i need to order something today, further help would be awesome.
     
  9. Rage_3K_Moiz

    Rage_3K_Moiz Sith Lord Posts: 5,431   +28

    The multiple rails are purely internal and to put it simply, for PSUs that support SLI or Crossfire and have more than two rails, one rail is dedicated to each PCI-E connector, so each video card is on its own rail. This prevents the video card from pulling power from the other rails that feed the CPU and other peripherals and causing an overload. In a single-rail PSU, all components pull power from the same rail, but cannot overload it unless one or more of them pull more power than the rest. So single-rail and mutli-rail doesn't really matter, what ultimately matters is the quality of the PSU and its total combined +12V wattage and current, not the individual currents on each rail (the total +12V wattage is usually specified on most PSU stickers). The ToughPower 850W has a combined total current output of 62A, while the Mushkin's total +12V current output is 64A, more than enough for two GTX 260s. If you want another alternative to all those PSUs, this is an excellent one, with 64A on the +12V rails combined and a nice price combined with free shipping. I wouldn't go for the Mushkin though. The actual choice is upto you.
     
  10. alisbin

    alisbin TS Rookie Topic Starter Posts: 93

    thanks a bunch rage, getting that antec PS, seems like the best deal (with great ratings) of all of them, though i'm curious why you recommend against the mushkin which seems almost identical. i've never used any mushkin products, but i've heard their RAM is great, are their PS low qual?
     
  11. Rage_3K_Moiz

    Rage_3K_Moiz Sith Lord Posts: 5,431   +28

    The Mushkin PSU is made by Topower, who've had mixed success with all the manufacturers they've produced for.
    The Antec on the other hand is made by Channel Well Technology who, while having had some bad phases of their own, now produce some of the best PSUs out there, ranging from the excellent Corsair 550VX, 650TX and 750TX range of PSUs, as well as some great Gigabyte (Odin Pro and GT), Thermaltake (including the ToughPower 850W model I recommended before) and XClio models. The PC Power & Cooling Silencer 750W model is produced by Seasonic, who are possibly the finest PSU manufacturer and right up there with other great OEMs like FSP, Delta and Enhance.
     
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