400W not enough?

By Vehementi ยท 35 replies
Dec 23, 2002
  1. Hi,

    I just had a random reset...it just happened as I scrolled down on a page, nothing really PSU intensive. I've had the same thing happen twice before. I have a 400W PSU, but it shouldn't be the problem...:(...Is there anything else that may be causing this? Windows errors? I do get a few BSODs here and there...

    And I'm not (currently) overclocking at all.

    The thing is, 400W should be plenty for what I'm running! My specs are in my profile...It's not like I have 8 HD's or something like that.

    Any help is appreciated.
  2. iss

    iss TechSpot Chancellor Posts: 1,994

    all power supplies are not created equal. some 200 watt PSU's actually outperform some 300 watt PSU's. many cheaply made PSU's deliver less than HALF of their rated power output. on top of that many manufacturers are still not pumping up the 12V rail. modern Processors like athlon XP's and P4's draw power fromthe 12v rail and any power supply that doestn provide at least 16amps on the 12v rail is one I wouldnt buy.

    Check the 12V rail for output on your 400W if it is less than 15amps it isnt sufficient. when I built my 2 ghz P$ I tried to use the 300 watt PSU that came with the case it wouldnt even boot the system checking the PSU I found that it only put out 10 amps onthe 12V rail the P$ 2 ghz draws almost 9 amps by itself. I got a 420watt PSU that puts out 18amps on the 12v rail and no more problems.

    here is a link to an excellent article on power supplies

  3. Vehementi

    Vehementi TechSpot Paladin Topic Starter Posts: 2,704

    Thanks for the great link iss...

    Well, after reading that article in it's entirety, I cracked open my case to read the following off the top ( :dead: ) of my PSU:

    +3.3V - 28A
    +5V - 30A
    +12V - 15A

    Add that all up and I get a total peak value of 425 Watts !! :eek: (I guess I'll have to update my specs ;))

    Anyway, it says 15A is the bare minimum...

    That's not too bad is it? I really don't want to have to buy a new PSU.
  4. iss

    iss TechSpot Chancellor Posts: 1,994

    15A on the 12V rail should be sufficient as long as you dont have more than one hard drive or several case fans. if you have acess to another power supply you might try hooking it up and seec if the problem continues.

    since this has happned before while scrolling maybe you should check your mouse and drivers. what kind is it? try another mouse and see if the problem continues
  5. vassil3427

    vassil3427 TS Rookie Posts: 640

    Hey what brand is it Veh? Cause I know the cheapo 400w have extremely poor internal circutry most of the time, and can cause problems after you've had them for awhile(been there too)....

    But I have a question about P.S.U. problems myself, recently after upgrading my parents pc form a 700mhz Duron to a 1.2Ghz Duron, It started freezing, just a dead freeze, it seems to be doing this all the time, whenever it wants too, I managed to fix it for awhile by disabling the power saving modes in the bios and in windows, but the problem is worse now, It has a cheap 250w PSU in it, Is that not the problem? Oh and I added a strip of 512mb too....

    I flashed the BIOS too, didnt help....
  6. iss

    iss TechSpot Chancellor Posts: 1,994

    if I am not mistaken AMD specifies a minimum of 300 Watt PSU for athlonXP's and newer durons. I doubt the 250 watt PSU has sufficient amps on the 12V rail to be reliable for the duron.
  7. Vehementi

    Vehementi TechSpot Paladin Topic Starter Posts: 2,704

    I have 2 HDD's + 2 CDROM's + 9 total fans...:eek:

    I have access to a 300W El Cheapo(TM) that wouldn't put me any better off than this one.

    My mouse is a Logitech USB Optical Special Edition (M-BJ58), and I just downloaded the latest MouseWare I think a week ago.

    I disabled a couple of my onboard features (LAN, sound) from my BIOS, just now, so that should help.

    vassil -> Here's my PSU, except I got the silver 400W model, and it was alot more expensive when I bought it...around $70 I think. Mid-range PSU, IMHO. Not El Cheapo but not excellent :D Well built PSU, IMHO, very quiet, no electric noise, voltage deviation is minimal.
  8. SNGX1275

    SNGX1275 TS Forces Special Posts: 10,742   +421

    That might be it, the RAM, take out the old RAM and just run the new 512 for a while, if the problem continues it could be the RAM. You can verify that by running just the old, if it runs fine 1 of 2 things could be happening:
    1. You got a bad 512 module.
    2. Your old and new RAM don't get along with each other. (could be due to different CAS latencys or speeds, or just general incompatability).

    It could be your PSU as well, but I'd bet on the RAM first.
  9. iss

    iss TechSpot Chancellor Posts: 1,994

    QUOTE]I have 2 HDD's + 2 CDROM's + 9 total fans...[/QUOTE]

    LOL sheesh Veh you got a hot tub in there too?:D

    15A aint gonna cut it with two hard drives and nine fans. even the 330 true power antec PSU's deliver 17A on the 12V rail and most good quality 400W Psu's deliver 18A

    the new Vantec 470W PSU's are delivering 28A on the 12V rail I am willingot bet that if you upgrade to a PSU that delivers at least 18A 12V that your restarts and blue screens will disappear.

    Take a look at the thermaltake PSU 420W at the bottom of this page it delivers 18A on the 12V rail and is a good quality PSU and its only 59.00

  10. iss

    iss TechSpot Chancellor Posts: 1,994

    Take a look at the output of power supplies first your raidmax

    Raidmax 400W +3.3V 28A, +5V 30A, +12V 15A,

    thermaltake 420W +3.3V 30A +5V 40A +12V 18A

    Antec 430W +3.3V 28A +5V 35A +12V 20A

    Vantec 420W +3.3V 26A +5V 42A +12V 18A

    Vantec 470W +3.3V 26A +5V 47A +12V 28A
  11. Phantasm66

    Phantasm66 TS Rookie Posts: 5,734   +8

    i am running with 4 hard drives, 3 cd rom drives, all PCI slots filled, athlon c, case fans, etc, etc...

    and i have 400W PSU and all is fine. I think your problems are elsewhere.
  12. Nodsu

    Nodsu TS Rookie Posts: 5,837   +6

    You can look up tech papers on all your components and get the peak and normal wattage for most of them. Then just add up and compare.


    IMO blaming the PSU first for a random crash is a bit silly. Maybe Veh is just boasting with his 400W PSU.. :D
  13. silky

    silky TS Rookie

    interesting thread i don't know how my computer is still running with all the kit i got inside. (take a look at the profile to see whats inside) the spec on my psu says +3.3v = 28a, +12v =10a, +5v = 30a and it hasn't let me down in a year and runs flat out doing lots of video crunching and when it's not doing that it's running the UD agent 24/7.
    I have been running video compression for the last few hours and still is, I just checked the voltages with Sandra and I got board 30c cpu 45c 3.3v = 1.5v 5v = 4.62v 12v = 11.75v stand by = 4.82v.
    It's a Chinese century star psu I think they rated it at 350w and it is superbly put togeather. it has a secondy fan in the event of overheating and to the best of my knowledge it has never ran, maybe it's bust :D
    Quality has a part to play along with the numbers.
  14. StormBringer

    StormBringer TS Maniac Posts: 2,244

    I don't know many people who run enough stuff to need 400W. I have a 400W but the last time I checked the values, it came out to 309W being used.

    The values you guys are reading are what the lines are each rated at, and not meant to be applied all at once. It means that the +12v is capable of 28A but if you maxed out each of them then you'd overload the PSU. While you can max one or more lines, you'd have to take the others down or else it would overload. Those ratings are pretty much meant to apply to what the wire can handle, they don't have too much to do with the rating of the PSU itself. If they wanted to, they could put wire on each line capable of handling the entire rating, but that wouldn't be very good for other reasons.

    You might also want to consider that your line voltage may be fluctuating. In the US, the electrical code is very loose on what 120v actually means. it can vary from 105v to 125v at any time, I have even seen some lines that go down to 95v at times. The only cure for this is a good line conditioner. Unless it dips below 95 on a frequent basis, then the power company may fix it.
  15. iss

    iss TechSpot Chancellor Posts: 1,994

    True, 400W should be sufficient...unless the PSU isnt really delivering the output it says it is and that unfortunately is quite common. if the raidmax isnt delivering the output it claims to deliver or it is having problems then 2 HD's and 9 fans may be more than it can take
  16. Vehementi

    Vehementi TechSpot Paladin Topic Starter Posts: 2,704

    Buying a new PSU is easier said than done :rolleyes: Great, another Thermaltake product to put in my box...(Thermaltake Xaser2 5000A case, Tt Volcano 9...)

    Is it at all possible I can somehow avoid this and not have to buy a new PSU?

    And if I find a generic/other brand that has 18+A on it's 12V rail could I get that?
  17. iss

    iss TechSpot Chancellor Posts: 1,994

    well...it might not be your PSU the fact that this happens when you are scrolling is a bit suspicious was this happening BEFORE you installed the new logitech drivers?

    you might try unhooking a couple of the fans to see if it is the PSU if you arent overclocking then one fan blowing air in and one blowing out should keep your system cool at least long enough to see if it is the PSU.

    BTW you do have good fan grills in place to keep small children from being sucked into your homemade wind tunnel there dont you?:D
  18. Rick

    Rick TechSpot Staff Posts: 4,572   +65

    I'd look more toward drivers or overheating as a cause for this. Check your Windows 2000 or XP even logs for any recent indictions of problems... If you have 2000 or XP that is.

    Switching between ACPI/APM may help if this is a driver/hardware issue.
  19. Vehementi

    Vehementi TechSpot Paladin Topic Starter Posts: 2,704

    Well I don't think it's my mouse, I mean it's just that it doesn't seem like it. It was probably a coincedence that it resetted when I scrolled down. It actually scrolled down then resetted.
  20. Vehementi

    Vehementi TechSpot Paladin Topic Starter Posts: 2,704

    Overheating is not the problem Rick, as I have 3 (40CFM)intake fans and 4 (2x 40CFM, 2x 25CFM) exhaust. 120CFM in, about 130CFM out. I'm perfectly cool :D

    The 500W Raidmax has 25A on the 12V rail...I might get that...especially since it's so cheap...
  21. Vehementi

    Vehementi TechSpot Paladin Topic Starter Posts: 2,704

    Or, is 18 amps enough? That doesn't seem like it, because 15A isn't. I could just buy the 420W Tt.
  22. iss

    iss TechSpot Chancellor Posts: 1,994

  23. Vehementi

    Vehementi TechSpot Paladin Topic Starter Posts: 2,704

    That's a great read iss - thanks again.

    Could I possibly buy a 350W Enermax? If I'm reading this ( EG365P-VE)correctly, it says the 12V rail as 26A available...:eek:

    Plus it's $43 :D
  24. iss

    iss TechSpot Chancellor Posts: 1,994

    the enermax would be a good buy. other good brands are antec, vantec, and thermaltake and of course PC power and coolings PSU's but they are very expensive.
  25. Vehementi

    Vehementi TechSpot Paladin Topic Starter Posts: 2,704

    350W Enermax it is then! I'll order it now.
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