400W enough for my new pc?

I have a Zalman 400W ready for my ordered pc:

core 2 duo E6600 (2.4GHz)
Geforce 8800 GTS
2 WD Raptors in Raid 0
2 GB DDR2 800 Mhz RAM
P5B-V motherboard.

I dont know much about electricity and shit like that :)
The side of the PSU says something like "380W allowed - 400W total"

I'd really like some information about how you calced if this will be enough :)

thank you in advance for the help
7 answers Last reply
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  1. With PSUs - You only need to ask yourself one question:

    Are they on both the nVidia SLI Certified, http://www.slizone.com/object/slizone_build_psu.html#certified_powersupplies , and

    ATI/AMD Certified, http://ati.amd.com/technology/crossfire/buildyourown2.html , PSUs lists ?


    And no, it is highly unlikely a 400 Watt, even a Zalman, will last very long (eg: over 6 months) with a GeForce 8800 GTS installed. If, or rather 'When', it fails it may damage other hardware in the process.

    Stick to the certified lists above, and you'll make the perfect choice, first time, every time. If not go one level (+41.43%) higher wattage than you think you need, it'll last you through more upgrades and reduce chances of problems when the PSU is 3+ years old.
  2. A lower rated but good quality PSU will handle power demands with much more ease than a high rated no-name PSU.

    Refer to

    for a realistic evaluation of the power consumed, these are system totals btw, not just the video card. Nvidia and ATI purposely inflate the power requirements on their card description since they are aware that most are using bad quality PSUs that cannot provide (with stability) the amount of power they advertise. This is done to cover their ass really, not because a 8800GTX actually consumes 350W of power by itself.

    Unless you plan on heavy overclocking, you should be ok. TO be honest I dont know how much extra power raptors draw when compared to typical 7200rpm HDs, but it cant be more than 5-10W extra on each.

    Your PSU will be operating close to it's full capacity (in the 300-350W range) when you play games, but then again thats what it's supposed to do. If it fails, you buy another one. And make sure it's a quality unit (Antec, Seasonic, Zalman, etc ) if it does fail.

    Many people hastily recommend high power (500+ watts) PSUs to everyone, but few have bothered actually measuring their peak system draw to back up their claims. I have. My system draw tops out at 300W with an overcloked d805 (read : room heater) and a 7900GTO (similar draw to the 7900GTX). Make your own conclusions.
  3. It is often too low wattage on the 12V lines which is why 550+ watts are recommended.

    I'm also assuming he may want to SLI 2 x GeForce 8800 GTS later using the same PSU and Video Card (maybe diff mobo + cpu, who knows).

    Also PSUs lose about 30% of their efficiency over 3-5 years, which can really play havoc with the 12V lines.

    It is for these key reasons why many recommend just "a decent 550 watt PSU".

    The lowest PSUs I recommend people use are:
    - Antec TruePower Trio 650 Watt,
    - HEC GroupSigma 650 Watt
    - Seasonic S12 Energy Plus 650 Watt
    - Coolmax CW-650T - http://www.coolmaxusa.com/productDetailsPower.asp?item=CW-650&details=features&subcategory=120mm&category=single
    - Hiper HPU-4M670 (670W)
    - Mushkin XP-650
    - Seasonic SS-650HT 650W
    - Thermaltake PurePower 680W (W0049RU)

    In fact, I should make a stick on it.
  4. I'm fairly certain that at full load, my d805 @ 3.6 Ghz alone draws about as much power as his C2D and video card together.
    Everything has a lifespan, and 3-5 years for a PSU at reasonable load is not a bad one either. Better than the 6 months you mentionned previously however, isn't it?

    Both of you insist on getting the OP to upgrade to a PSU that in my opinion is well beyond what he will need. Having had to deal with power supplies on a somewhat "up close and personal" level when designing one to work with a custom built router as part of my final year project, I can say that this seems extremely redundant to me. Luckily I never had to deal with that kind of design afterwards (I dislike power engineering), but if I matched a 100W PSU to a router that only drew a peak of 20W, I would have failed my project course.

    All of his listed parts draw more power than yours do. His PSU will probably run under full load and require a tad more, and running a PSU under full load leads to the PSU dying relatively quickly (2-3 months?), possibly taking parts with it. It's not worth the few dollars that could get him a better PSU over the risk of frying his 8800GTS.

    I guess this statement stems from years of analysis of failed PSUs. This isn't James Bond you know ... these things are not programmed to self distruct (which is more than what I can say for DELL laptops lately). Any decently designed PSU can handle, with proper cooling (read : stock fan) a power load close to it's peak on a routine basis, let alone during periodic gaming sessions. And when they do die, there are many current safeguards (in layman's terms : a fuse) that will prevent any kind of unexpected spike from damaging the components. Obviously nothing is 100% reliable, but I'd be more worried about getting your PC stolen from your house than damaged by a Zalman PSU that crumbled under load.

    The main positive aspect I can see out of everyone on these forums recommending industrial-strength PSUs to just about everyone, is that their price is bound to come down by the time they will actually be needed in home computers.

    Keep it up ! :)

    p.s. I guess that's my last post in this thread. To the OP : I'm not claiming that my opinion is better than anyone elses, I just think it's reasonable. Getting a 600W PSU certainly wouldnt hurt you, akin to changing your oil once per month. I assumed by posting here your intentions were to avoid an extra 100$ cost if possible, since if money wasn't an issue, you would have bought a new PSU without asking (since you're obviously in doubt about it).
  5. Potential Sticky made:


    Overclocked that Core 2 Duo is only going to pull 100 watts or so. (eg: 3000 MHz at 1.375 Volts on a C2D = nearly exactly 100 watts for CPU).

    But yeah, the other parts will need some juice.
  6. Quote:
    I guess this statement stems from years of analysis of failed PSUs. This isn't James Bond you know ... these things are not programmed to self destruct (which is more than what I can say for DELL laptops lately).

    I respectively disagree with this comment.

    PSUs are set to self-destruct after 3-4 years of use, in a way, as the cheaper ones will fail within that time frame.

    Sure he may have sold the PC to someone else, Video and PSU inclusive, but then that just means the problem is delayed, not avoided.
  7. The response I got on this question is awesome.
    A big thanks to everybody for posting your ideas and thoughts, and the many interesting links. The discussion was very educational for me.

    I think I'm gonna do like redwing and measure out the load.
    Next week, when my pc arrives, I'll post the result here for the record.

    From what I read here, it seems most likely that I wont have much reserve left, which means I'll have to replace my PSU anyway when I do some overclocking or upgrade a component.
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