This topic contains 44 replies, has 0 voices, and was last updated by  Rommel 8 years, 2 months ago.

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    *sigh * once again over my head..

    I have need of a large supply due to degredation of the power supply, and a top of the line graphics card, ATI Radeon HD 4890, i was thinking of expansion in the future with probable multi graphics cards hard drive, ram, ect.

    My computer is a very nice machine, but i need a reliable power supply, and for the prices i see for 650 watts, i might as well just by a 800 watt for the same price.

    my price range for the power supply is 80-100 USD, seeing as how anything less than 80 could be another crap purchase like the last one i bought!

    Thanks for the Help!

    KB 😀



    well i usually give people and example of how much they might need ..

    basic rule, you dont need more than 450w maximum even for sli system.

    my specs are

    amd phenom x4
    2sticks of ram
    8600gt graphic card

    i run it all on 350w without any issue ..
    a cpu would consume most power that being around 150w maximum..
    if you plan on a high end card, it would use a little more than the cpu, say 180w which is still 330w grand total … besides these you power hdd and all other stuff comes mostly to 100w which is 430w. (100w is very unlikely for anything under a cpu) …

    buy a good 450w psu, stay away from anything more than that..
    a 800w psu priced same as a 450w will be a piece of ****.

    P.S- dont get caught up in the high wattage hype. its all nonsense.


    Laptops Daddy

    a pc psu watts rating means nothing at all. ignore it. its only useful for comparing one manufacturers range so you know which are their higher end models.

    listed max 12v output means something, but very little.

    try this google search. there are some worthwhile links near the top.

    @Kangabunny wrote:

    for the prices i see for 650 watts, i might as well just by a 800 watt for the same price.

    no! thats exactly what ive been trying to get at. reverse that idea and you’ll be fine : )

    quality is everything.



    Wattage means a lot, but does not necessarily mean higher is better. Usually an expensive psu of a lower wattage is high quality. 12v rails and every other little stuff comes well in a high quality psu. just compare the wattage and price.

    get an expensive low wattage psu rather than a cheap high wattage one.

    To ease your confusion, pick a wattage below 500 (500 is very high but iam suggesting because iam sure you will be very insecure getting a 400w) and get a corsair psu. they supply all kinds of cables even with a low end smps so you dont have to worry about that. Dont but above 500w though, your just wasting money.



    I would not suggest a power supply rated lower than the factory model. However, I do suggest that you might want to investigate the cause of the failure before you install a new one.

    @Kangabunny wrote:

    *sigh * once again over my head..

    Thanks for the Help!

    KB 😀

    I can not recall a failed computer power supply that actually fried, being caused by anything other than excessive heat. This could be due to failure of the fan motor, excessive dust build up which restricts the air flow or brown out conditions. Fan monitoring and regular cleanings (twice a year) will help ensure proper air flow and help keep your other components cool.

    The only other thing I saw with regularity that wasn’t an overheating issue was a blown fuse or a blown “resitor fuse.” Generally, this was due to someone trying to “force fit” a power plug. It can be done, if you are determined.

    If it is a blown fuse (either type) caused by shorting, it is an easy fix. Open the P.S. case (THIS WILL VOID THE WARRANTY) and check the fuse. If it is blown, check the fan. If blowing on it turns the blades, replace the fuse and fire it back up. If the fan is binding, replace the fan before proceeding.

    Note : Electronic equipment that is operated within the specified parameters should follow the bath tub falilure curve. Failures are most likely in initial use or after many hours of operation.

    .. .. High Failure Rate
    . .
    . .
    . .
    ............................................. Low Failure Rate

    Length of Time in Service

    To ensure that you have a safe and dependable power source, you may want to consider an uniterruptable power source (UPS). This provides protection against noise on the incoming line and brown out conditions.

    Brown outs are very bad. Perhaps you or one of your neighbors are periodically pulling down your line voltage. You can monitor the line voltage if you have the proper equipment. If not, you can request a recorder from your local power company and monitor it with their equipment.

    Best wishes


    Laptops Daddy

    i like that graph : ). useful info, rommel.

    i think very little of taking a soldering iron to a psu, personally. and ive had plenty go bang. you should never take the cover off if youre not completely confident that you know what youre doing*. usually when a fuse fails, its for a reason. if you replace one, be ready for a loud bang when you test it.

    and remember you can get a nasty shock from a psu even when its unplugged.

    ive often put power supply failure down to excessive dust build up (dust can be slightly conductive and cause shorts)

    (*if ever i set up a custom pc or service something older, often one of my first jobs is to undervolt or replace the psu fan)



    I suspect that the majority of people retire personal computers
    before the P.S. should be expected to die from old age. If you
    have had several to fail, it seems that you have a problem that
    is not related to the expected life cycle of power supplies.

    I have only had one to die on me and that was in 1991 (I think).
    It was in a Northgate 20 Mhz. 386 – DX.

    The fan froze and due to the location of the machine, I failed
    to notice before the power transitors failed.

    Since it was out of warranty, I replaced the power transitors and
    installed a new fan. However, being a bit bold, I decided that I
    would reverse the flow and pull the heat from my other components
    out through the P.S. instead of blowing the heat from the P.S. into
    the case as it was originally designed.

    Yes, I took a chance of overheating the power supply but the
    power supply was about the cheapest component in the machine.

    The upgrade from a 40 MB HD to a 200 MB was about $ 1,000.00
    The memory was $ 100 per Meg and it was fully loaded at 4 MB
    I don’t remember the cost of the CPU but I think that the cost
    difference between a 20 Mhz. and a 25 Mhz was about $ 400.

    The power supply, if I had chosen to replace it, would have
    cost about $ 45 to replace.

    I thought it wise to protect the more expensive components
    and risk damaging the cheap one.

    The machine operated almost continuosly for the next 5 years
    and was still operational when it went into the attic.

    P.S. – The graph looked fine when I previewed it but had to be
    modified to display properly after I made the post. It should
    look better now.

    P.P.S. – I have had to replace a few fans over the years. The
    two for my laptop were not only fastest to fail, they were also
    the smallest and most expensive. It runs almost continuosly
    and has for several years.


    Laptops Daddy

    @rommel wrote:

    The graph looked fine when I previewed it but had to be modified to display properly after I made the post. It should look better now.

    looked fine to me when i first saw it. i wasnt being sarcastic.

    @rommel wrote:

    If you
    have had several to fail, it seems that you have a problem that
    is not related to the expected life cycle of power supplies.

    yes. just a numbers thing. thats one of the reasons i (think i ; ) know all this crap. ive worked with computers a lot over the years. theres no reason a decentish psu shouldnt last the life of the pc, plus upgrades and then some.

    ps: i know. amazing how things have changed. im not quite that old, thankfully : ). 8MB main ram was about £200 when i first got into PC maintenance. just about the time 72pin edo ram and 32bit pci slots were taking over. (mid to late 90’s?). i remember when 8MB ram total was considered a LOT and 512MB hard drives were huge



    Do power supplies still come stock with the air flow intended to protect the P.S. at the expense of the the other components?

    It is understandable if they do. That is, in the sense that they aren’t charged with protecting anything else. With additional case fans, perhaps it isn’t an issue either way but it seems that on an overclocked machine, dumping the P.S. heat to the outside would be the better option.

    My boss told me not to reverse the air flow on the P.S. or I would burn it up again. I tried to argue that if it was unable to cool sufficiently, using the preheated case air, it was poorly designed. It was generating far too much heat and/or the cooling capacity of the heat sinks was too small for the transistors.

    He expected it to die swiftly but it was still running when he went out of business. One of only a very few places that failed shortly after my departure. Of course I think I was that crucial to their operation. What else could I think?

    Best wishes



    airflow on power supplies these days from my experience is that they are exhaust fans that empty into the room.



    Thanks ORCACommander.

    On the expected failure rate :

    There are always exceptions. Sometimes it is a faulty component, sometimes a faulty design. The Hitachi light engine that was used in a great many LCD Projection TVs was improperly designed. They had a predictable heat failure which occurred early into the expected life of the set.

    The case and fan combination did not allow adaquate air flow to cool the color filters. Over time they suffered discoloration due to heat stress. The repair cost was high and the replacement part was the same as the orginal. Newer models use a modified light engine which is supposed to afford adaquate cooling. Time will tell.

    NEW !!! 1 TB 1 M RPM HD !!! MTBF – 20 YEARS !

    Did they run it at 40 M RPM for 6 months without burning out the bearings or is that simply a guess ???


    Laptops Daddy

    thats an interesting topic – airflow. its almost a shame we dont have a dedicated thread. it is quite fun hijacking this one, but – maybe we can get an admin to move us?

    my opinion is that a pc should be treated and cooled as a complete system. im sure lots of people have different ideas.

    pc cooling has been less an issue for a few years. with heat pipe coolers, stepping technology etc and variable speed fans. the whole thing came of age.

    i wonder if we might see some further innovation. things are moving towards smaller, prettier pc’s that look good in main rooms (plus more parallelism – things are getting more tightly packed all the time). there are many cases now that offer psu mounting points bottom front or in non-standard locations out of the box. htpc’s and absolute silence can still present pretty big challenges, even with new energy efficient hardware.

    @rommel wrote:

    Do power supplies still come stock with the air flow intended to protect the P.S. at the expense of the the other components?

    i dont think they ever did. the usual design was an 80mm fan exhausting out the back of the psu. that was the case since the advent of what we’d recognise as a pc psu. it would no more protect the other components to reverse the air flow. (same applies to modern 120mm designs, doesnt it?).

    heres an old one. back in the days of block shaped solid sinks, you know, the traditional chunk of aluminium with a fan mounted flat. there was a question of whether the fan should blow onto the sink, or exhaust from it.

    i think in theory its better to have a fan exhausting heat, but that breaks down when there are other hot components surrounding the cpu. there are a lot of variables. im not sure theres any fixed rule. im getting a little nostalgic



    you want to learn about cooling?

    go here



    I wasn’t intending to stray from the P.S. topic. (if that is the topic)

    On a multiple fan system, where some fans are intaking and others are exhausting, regardless of the flow rate desired, maintaining the case pressure as close to zero as possible, should be the goal.

    Under the original ATX power supply standard, the air flow was mandated to intake from outside the case and exhaust into the case. The standard was later modified (Shazzam!) to allow air flow from either direction. I have no clue what the standard says now.

    The rate and direction of air flow on the new power supply will effect the case pressure. This will have an effect on the overall cooling capacity of the case and the life of all the fans.

    Whether building your own multi-fan system or installing a non-OEM power supply, maintaining a zero case pressure should be the goal. This can be a tough balancing act.

    Best wishes to all



    The only air flow im getting is your guys long winded replies about power supplys (haha)

    Nah ty for your guys help, i decided im going to purchase one of theese:D

    brands have gotten good ratings across the board, and was highly recommended by quite a few.

    The old power supply was a failed antec earthwatt 650PsU. It was a manufacturers default in the power cord switch or something, i took and had it inspected at the store i purchased it from. They marked it as defective and gave me a refund (- 15% damn) and charged me a restocking fee. I will never buy from them again.

    Any problems with the aforementioned links psu?
    I have a ATI radeon hd4890 graphics card, and it has the two six pin pci-e cords i need ( i think?) . So i hope this is a good purchase, will probably be purchasing it tommorow.

    Ps. My case has quite adequate cooling, it has plenty of air flow, my dad designed the computer with that in mind. (thank god as i am totally lost when it comes to theese things, Art is my forte.)

    trying to decide wether to get overnight shipping or not, is it worth $25, or even 2 day delivrey for $16.95? itll still be cheaper than what i paid for the Failed Antec PsU.

    (never bought online btw so alittle nervous making a purchase with my debit card, is newegg ever ripped you guys off?)

    Thanks 😀

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