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View Full Version : Need new Power Supply if upgrade Mboard & Chip?



Steve_L
30-09-2002, 07:06 AM
My 400 Mhz Celeron needs upgrading, and I am planning on getting a new motherboard-chip-RAM unit. They cost around $350 - $800, so it seems like a good way to go, seeing that I do not need to replace the CD Writer or HD (not quite yet), CD ROM, etc. But how do I know if my old power supply will support the likes of an Athlon 1800 or 1.7 Celeron, etc.? I suspect that I will need a more grunty PS as the one I have is just 240 watts and my guess is that I need around 300 watts. Is this true? Is there some place on the Net where it says how much power is needed for upgrading?

BTW, if I do need a power supply then I guess it might be best to get an upgrade box, such as what PB Technology sells. Right?

Thanks - Steve

MoNk
30-09-2002, 09:35 AM
You shouldn't need to waste your money on a new PSU.

Until recently (i added alot of fans to my case and some other stuff) I was running a 200W (amazing I know) on my XP1800+.

A safe bet is a 300W though. And they only cost $60 (if you pay more you're getting ripped off). This should last you a while.


As for your upgrade box. These are the cheapest prices I could find.


Internet Upgrade Box $445 inc GST
AMD Duron 1.2GHz CPU & Fan
PC Chips M825LMR Motherboard
128Mb PC2100 DDR266
Integrated Graphics (+ AGP Slot)
Mid ATX Tower Case 300w
Integrated 56k Modem
Integrated Sound
Integrated 10/100 LAN


Gamer Upgrade Box $875 inc GST
AMD Athlon XP1800+ (1.53GHz) CPU & Fan
Soltek 75DRV5 Motherboard
256Mb Vdata PC2700 DDR333
Leadtek 64Mb DDR GF4 MX440 Video Card
Mid ATX Tower Case 300w
Integrated AC97 Sound
Fully Assembled


Those include your new 300W PSU. And in my opinion and many others Soltek delivers the best Motherboards. Sadly the second includes a gf4mx but that can be easily swapped.

Graham Petrie
30-09-2002, 11:02 AM
> A safe bet is a 300W though. And they only cost $60
> (if you pay more you're getting ripped off).

For a basic PSU, yes. BUT, you do get what you pay for. Just because it costs more, doesn't mean you're being ripped off. It just mean you are buying quality and reliability. A cheap PSU doesn't deliver as clean power as an expensive one. You may not notice those tiny fluctuations while you use the PC, but it will shorten the life of your components. In my opinion, it is better to buy a smaller, but better quality PSU than a bigger , cheaper model as long as the smaller one is big enough to power everything OK.

BTW re: your 200W - you may get away with this, but ther est of your components will be suffering. There are reasons for having the corretc size PSU - if you are putting too much pressure on the one you have, you will be wearing it out, not to mention the fact that your components may not be getting the juice they neeed during peak usage.

Your call.

AMD has an article on how to figure out the power requirements of your system here (http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/26003.pdf) (Page 5 onwards)

G P

MoNk
30-09-2002, 11:18 AM
I agree that PSU quality greatly differs. It is the most underapreciated part of your PC. It is also the most easily damaged.

I simple 300W ATX PSU does the job, and is a trusted product. The only other trusted brand is Enermax which produces mainly 350+ wattages and is very expensive. They are only expensive because they want you to buy the cases that acompany them however.

Do you have ESP or something? How do you notice these tiny fluctuatoins you speak of?

I've read those power supply articles before on AMD's site + others. They just say your MAXIMUM DRAW. But the reality is your computer will NEVER draw the amount of power you add up from all your components, NEVER EVER. Those sites always seem to be selling things also. You'll find overclocking sites are far better at explaining things truthfully without weighing their comments with products.

You will also find that there are NO SMALL WATTAGE high quality PSUs available anywhere. You may be able to get a 250W "good brand" PSU, but you won't find many.

tweak\'e
30-09-2002, 11:47 AM
>The only other trusted brand is Enermax which produces mainly 350+
>wattages and is very expensive. They are only expensive because they
>want you to buy the cases that acompany them however

?:| you can buy enermax psu's without cases no worrys. there are a fair few good quality psu makers around.

>are NO SMALL WATTAGE high quality PSUs available anywhere.

most are found in OEM machines eg hp/compaq/pc co.

one thing not to forget is to get an AMD style psu. these have grills underneath(or a fan) to allow hot air from cpu to be quickly removed.

Graham Petrie
30-09-2002, 12:00 PM
>The only other trusted brand is Enermax
> which produces mainly 350+ wattages and is very
> expensive.

Bollocks - there are other good PSU manufacturers out there, but I agree that Enermax is definitely one of the best.

> Do you have ESP or something? How do you notice
> these tiny fluctuatoins you speak of?

No, you use a multimeter - there are plenty available for sale that you can use to measure the fluctuation of the voltage from the PSU. If you are invovled in modifying your PSU at any stage, the first thing you do afterwards is ensure that the output voltages are correct and that they only fluctuate within the required specifications to make sure you don't blow your rig.


> I've read those power supply articles before on
> AMD's site + others. They just say your MAXIMUM
> DRAW. But the reality is your computer will NEVER
> draw the amount of power you add up from all your
> components, NEVER EVER.

True - if you actually read the article I pointed you to, you would find that it doesn't give the specific wattage required, but rather the equation to work it out. AND it says that you will never require the maximum draw of all you components combined. It gives a maximum factor of 80% by which to multiply the draw from your components to obtain a realistic figure.

> You will also find that there are NO SMALL WATTAGE
> high quality PSUs available anywhere. You may be
> able to get a 250W "good brand" PSU, but you won't
> find many.

Why do you think that is?? Because most people buying a new PSU either want a big one for an overclocked/modded rig and need a good brand, or have a machine that they onlytake out on sundays which has a dead suplly. they only need a cheap job. But, you can get a good, smaller PSU.

I suggest you read the AMD article, and do a little research before you post.

In regards to Steve's question - Steve, it all depends on what other components you have. It would probably pay to buyt a new PSU as 240W is a little low for a high-drain CPU AND a few optical drives etc. Do the calcs if you want - you maight be OK if your other devices are low-drain.

G P

MoNk
30-09-2002, 12:10 PM
>>Bollocks - there are other good PSU manufacturers out there, but I >>agree that Enermax is definitely one of the best.

eg?

>>No, you use a multimeter

So you sit next to your computer while running it normal > games > apps etc holding yuo multimeter measure it???? = stupid

Or do you get an app and use the motherboards voltage sensors? < do that.

>>I suggest you read the AMD article, and do a little research before you >>post.

I suggest you try some real world experiences before you link to people you "think" are right. Do you beleive everything you read on the net.

tweak\'e
30-09-2002, 01:11 PM
>So you sit next to your computer while running it normal > games > apps etc holding yuo multimeter measure it???? = stupid

no not really. the trouble with on board senors is they do not always read correctly.

connecting a data logging multimter to the psu rails is a good way to do it as you can read the voltage as the pc starts up (which is impossible for a pc ap to do) and keep track of any dips in the supply. for the real fussy people connect up currant meters to.

something you guys need to remember is the wattage quoted is the overall wattage not the actual wattage for each rail.

running an old (possibley cheap) 240 watt psu on a new rig is just asking for trouble.

MoNk
30-09-2002, 01:39 PM
so you're saying the bios voltage readouts are wrong? why don't they read correct readouts?

everyone i have asked about this thinks that they are so close to correct there is no point in checking further.

tweak\'e
30-09-2002, 04:28 PM
yes they CAN be wrong, just like some temp readings are wrong. however for general monitoring its fine and it gives you the actual motherboard voltages instead of psu voltages. however if you are testing to see what the smallest psu you can get away with (as an OEM would) then an accurate multimeter is the only way to go.

Chilling_Silence
30-09-2002, 04:33 PM
You might have to upgrade, I know that there are some motherboards that support bothh the old poswer supply's and the New ATX supplys (I forgot the techy name for the older ones... :s)
If that's the case, I bought a Tower Case and a 250Watt Power Supply for $60 and haven't looked back!

Cheers

Chilling_Silence

MoNk
30-09-2002, 04:35 PM
im sure that sounds a bit out of contorl to most people! :)

godfather
30-09-2002, 04:39 PM
When you consider that an accurate multimeter can cost more than the motherboard (which does not have voltage measuring as its primary function) tweak'e is quite right.

A high-count meter will also respond to variations that wont be seen on the on-board monitor function, and its these excursions that can be critical.

Its easy enough to measure it approximately with a sensor but I wouldn't rely on it as being exact. Same with temperature. The motherboard will only be using basic a-d conversion for reporting compared to a good multimeter.

Graham Petrie
30-09-2002, 05:28 PM
> So you sit next to your computer while running it
> normal > games > apps etc holding yuo multimeter
> measure it???? = stupid
>
> Or do you get an app and use the motherboards voltage
> sensors? < do that.

Not so stupid actually. that is exactly what I have done in the past when playig with PSUs. Obviously for general use, or t determine if there is a mjor prob in a preiously working unit, the mobo sensors are OK, but if you have a PC that is playing up, and the problem does not seem to be anywhere else, the only way to do it is with an hour or so monitoring the PSU under various conditions with a decent multimeter.

> I suggest you try some real world experiences before
> you link to people you "think" are right. Do you
> beleive everything you read on the net.

I didn't link to anyone, but to an article I thought might help steve. You should take your own advice before you make a bigger fool of yourself than you already have.

G P

MoNk
30-09-2002, 05:31 PM
arrogant.

Terry Porritt
30-09-2002, 06:01 PM
Cool it fellahs. As regards voltage readings by the BIOS etc or voltage settings by jumper, just think a moment, voltages to 3 significant figures? No way are they going to be accurate. Eg my cpu core voltage reads 3.49 instead of 3.3; 1 in 300 roughly, 0.3%, better than a Fluke multimeter? No way, so dont believe all that you read :)

I would "believe" an accuracy of maybe 5%, without the benefit of a proper calibration.

PSU voltages; it is the spikes that can cause problems, you cant even see them on an ordinary analogue scope, you would need a bit of special transient recording instrumentation to see those. All a multimeter will do is to measure 'steady state' droop of the voltage regulation with current load.

MoNk
30-09-2002, 06:13 PM
3.3 is whats set 3.49 is actual.

mine is 3.3 set, reading 3.33

Graham L
30-09-2002, 06:35 PM
My watch shows "6:34 39". I know that the time is about 6:34 (because the watch has a drift ... it's nearly up to the minute fast at which I correct it). I say "It's about half past six". Digital displays show numbers. The numbers are only as correct as the circuit which produces them.

A digital voltmeter's accuracy depends on its reference source, and the uncertainty of the comparator, and the number of bits it uses. The temperature dependence of band-gap references is such that they need careful compensation. They don't put references that good on a motherboard. That costs money.

That reading of 3.49 on a 3.3 voltage is about 6% high. Pretty good. But not as good as a proper meter. My Fluke cost $535. I'd trust it for 3 digits (though I'd still use a scope to look at the line If I saw funny readings).

The sort of A-D converter used on a MB would be about as good as the "A-D" converter used for resistance measurements on a joystick interface. But I would not trust that to better than "1-1/2" digits.

A better supply will be better. But one that's good enough will be good enough. An overloaded supply will shut down. The test will be at startup. All the disk drive motors will be pulling their start current, which will be several times the normal running current. (Just thought I'd put in something on topic :D).

Steve_L
30-09-2002, 09:58 PM
Well well guys, you sure have given me lots to think about. LOL! I posted my Q early this morning and now checking F1 for the first time there are 17 replies, with controversy and even a few flames. Egad, I thought my Q was fairly simple. Ha! So what if I go the cheap way and stick with my old 240w ps? What is the worst that can happen - would the ps just fry and sizzle rather than other components? If there is a chance that an underpowered ps would cause damage further along, e.g. the new mboard & chip & RAM, then of course I would get a new 300 w ps. Oh, BTW, I know that if I were to shut my eyes and just VISA card a $1,000 (or more) upgrade, then all would be nice and safe. I just think that many others here on F1 are in, or will be in, the same boat: wanting to upgrade to a faster mboard-chip - without shelling out big bucks.

So what do you say now? Thanks for your assistance...and....the entertainment! ;-)

tweak\'e
30-09-2002, 10:10 PM
the odds are you will need a new case anyway so it would best to get a psu with the new case.

running an underpowered psu risks causing brownouts which can cause severe damage to parts.

Steve_L
01-10-2002, 07:16 AM
<<the odds are you will need a new case anyway so it would best to get a psu with the new case.>>

Thanks Tweake, but why is this necessary? If the new motherboard fits in OK, then why get a new case? Ventilation, or? The reason I ask this is to weigh up the choice of just replacing the mboard/chip/RAM - and new power supply :) .... or .... getting an upgrade box.

tweak\'e
01-10-2002, 11:21 AM
main reason is cooling. later cpu run hottter (exspecially AMD) also the higher powered vid cards, hardrives etc all add heat. a lot of the earlier cases are just not designed for hot hot cpu's.

the other thing to think about is what you are going to do with old parts. you could sell it complete in case as an upgrade box to someone esle.