Computer Power Supplies

  georgemac 16:22 07 Oct 2004

Have been doing a little research into the power rating claims of various computer atx power supplies. Todays modern motherboards, cpu's and especially graphics all seem to demand more power from our power supply.

The general rule used to be for an amd athlon 300 watt would be sufficient.

The thing appaerntly that tells you how good you power supply is is the max load rating on the 3 main voltage rails.

In here I have a gold dual fan 450 watt output power supply - VIP seems to be the brand name - and it has performed well, now powering an xp3000, msi hard drive, 3 cooilng fans, 2 hard drives, 2 optical drives, an fx5600 ultra graphics card and a couple of usb devices.

+3.3v peak 28a max 14a
+5v peak 35a max 25a
+12v peak 16a max 14a

the peak readings apparently mean nothing, this is what can be supplied for a slit second.

an antec 350 watt output smartpower

+3.3v max 28a
+5v max 35a
+12v max 21a

no peak ratings given as they are not really vaild, so you can see the 350 watt psu easily outperforms the 450 watt psu. Apparently the 12 volt rail is now more critical with modern components.

My sons PC had an asusa7a266 with xp1700, and more or less the same set up as above with a geforce 4200ti graphics card.

It was running happily with a 300 watt solarmax psu supplied in a jnc case from ebuyer

+5v 20A
+12v 12A
+3.3v 15a

I went to fit a new msi6712 motherboard, bigger heatsink, same cpu (will be upgraded later) and other components, apart from the fx5600 ultra which is for this pc.

I got no post, no beeps and the fans seemed to be spinning very slowly. Tried both graphics cards and different memory sticks - same result - so I am guessing psu is to blame - only time will tell - will post part 2 next.

  georgemac 16:31 07 Oct 2004

decided I would buy a new power supply to see if this was the fault, and started to look at antec as they have a quality reputation.

looked at kelkoo savastore was cheapest for antec 350 watt smartpower mentioned above at £38.47 plus delivery.

Continued to have a look at their site and came upon this

SLK1650 Biege TAC Tower PC Case with 350 Watt PSU £41.92, so for around £4 more than the psu, was getting the same psu, a case which has an antec 120 mm exhaust fan fitted as standard (these are normally around £9!)

I ordered the case around 4.30 yesterday afternoon £47.21 inc delivery, and it arrived at 3.20 pm today in the north east of scotland. impressive service from savastore/watfor - I will use them again.

The case looks very good quality, if maybe not the best looking in the world, but it looks OK. Power cable and all fitings supplied with a novel ducting scheme with a fan on the side (if you want) to blow cool air directly onto the cpu cooler.

So hope to try it out tonight, will post results - hopefully not a duff motherboard!

  picklsey 16:54 07 Oct 2004

good luck with it look forward to hearing your results.

  georgemac 20:54 07 Oct 2004

connected the new antec psu and it sprang into life. will continue connecting up the rest now.

anyone gets a new motherboard/graphics card/cpu and no post or beeps - check the ratings of your psu.

  georgemac 07:41 09 Oct 2004

all rebuilt and running very stable - have fitted ddr400 ram but underclocking at 266 fsb, same as cpu.

The case is not the same quality as the cheiftec one I have, but is still extremely good for the money - as it was as good as free because for £4 more than the psu on it's own, got the psu, case & 120 mm exhaust fan, which shifts a lot of air.

There is room in the front for an 80mm fan to blow in, and there are 2 usb ports on the front which is very handy.

I would recommend the case to anyone building a new pc.

The only problem I had was with my coolermaster dream heatsink, which has a large clip to ease fitting (and it is great) but because of the design of the msi cpu socket the clip was hitting the psu at the top of the case.

I bent the handle part of the clip a bit and it just fitted - moved the pc back to his room, put it on the floor and heard the clip come off - a lucky eascape for me! Fitted the old coolermaster heatsink whic will be OK for the xp1700 and will have to get one with a normal clip when I upgrade the cpu.

  georgemac 07:44 09 Oct 2004

to all you system builders, what type of power supplies are you using?

I am impressed with the antec - but they are quite expensive - anyone using alternative makes which have good max output ratings?

for info for amd guy's, a lot of the new boards require you to connect the 4 pin 12 volt connector to the motherboard to power the cpu. If your board has this connector (believe p4 uses this) it is important that your psu has good 12 volt max output.

If the board does not have this connector, the cpu is powered off the 3.3/5 volt rails so they need to be strong.

  oresome 19:33 14 Oct 2004


Looking at your figures for the PSU's, the Antec 350W delivers 519.4 Watts, assuming it can deliver the claimed current on all rails at the same time.

The VIP 450W delivers 339.2 Watts on a continuous basis and 459.4 Watts peak.

The VIP 450W therefore would seem to be rated at 450W on peak figures. On the other hand, the Antec appears to be rated on a continuous basis at 350W, but the supply currents given are peak figures which couldn't be sustained.

About time that all suppliers worked to a common method of specifying o/p's, then you would know what you were buying.

  ste_bla 21:35 14 Oct 2004

good quality = expensive !

But do you want to run the risk of blowing everything?!

  georgemac 15:41 15 Oct 2004

I agree, you would know what you are paying for if there was a common standards.

The VIP has been fine for me, and I do not have a power hungry graphics card in here so think I will stick with it just now.

May consider sticking an antec in here in the future as well.

Looking at the antecs on ebiyer however, I noticed in the feedback that a few had blown within the warranty period!

  niknax 22:54 16 Oct 2004

i love my chieftec case!! but not when i decided to add a 3.5inch card reader? had to disable the front usb connections!!but it was ........worth it!! tidy cases!!


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