Could someone please talk me through PSUs requirements? I'm looking to upgrade the machine in my sig, starting with the Motherboard and CPU. I currently have a Corsair 400w PSU. My current CPU draws (i think) 65w. I'm looking at buying a Phenom 955BE, which draws 125w. According to this review on Tomshardware, my GPU draws around 251w peak. So does this mean that with the new processor and my current GPU, my 400w PSU should be ok? Or have i completely misunderstood the whole thing? I do intend to upgrade the PSU before too long anyway, along with the GPU, case, and pretty much everything else! But the Mobo and CPU are the first steps. I also have a Crucial M4 to install, but my current Mobo doesn't have enough SATA ports. Any help appreciated.
You would be cutting it close as the motherboard will take some power along with the hard drive or DVD drive. The hard disks will draw a larger current when spinning up sometimes up to 30-40W. You could try as those figures are the maximum the CPU will use and PSU makers usually overcompensate slightly to make sure it will meet the stated 400W. If you're determined to get it now I would suggest under-clocking it until you get your new PSU.
if thats the corsair psu, I'm thinking of, it should be pretty decent, in any event, if it can't handle the machine when you put the new parts in, (it should) just not power up, rather than powering up and exploding like the cheap c**p psu's do.
for the price of a 650 watt psu i wouldn't risk it, the psu you have a v good model but it is very under powered for the the job, If your strugaling for money i have a thermaltake toughpower 500watt going spare, ill only ask for the postage on it of approx £13 quid. it would tide u over till you can afford a more powerfull psu still 400 watts wont cut the mustard, doesnt matter the make of the psu!!! 500 youll youll do fine, but id still sugest a more powerfull one p.s. this isnt for sale to anyone else
Thanks for the advice, guys. As for whether my current PSU is a CX400 or not, i don't know. It says Corsair 400w on it, but without taking my machine apart i couldn't tell you any more than that. @darren1678 - Thank you very much for your generous offer. I may well take you up on that. Is there a private message function on Bit-Tech?
it should be enough.. if you upgrade cards you'll be looking around 180-230 watts over idle (or more if you go with nvidia) a bit more than the 120w pulled by the 4850.. corsair psu's are always underrated though- they do a good job with the 12 volt rail.. why everyone likes them doesn't hurt the psu's come in a velvet bag if you push a psu to it's limits though, you lose efficiency, or so I've heard from that asshole on johnny guru
Oh, very easily enough to power it. How old is your PSU though? I make a point of buying a new one every 3 years give or take, because over time they can loose efficiency and drop down the scale in other metrics, while increasing chance of failure. A decent PSU will work year after year but im planning on replacing my 3 year old PSU before the end of this year just for piece of mind. Use the old one as a backup or in a testing rig.
Don't be deceived by a wattage rating (high OR low)...it is not NEARLY as important as AMPERAGE. Anyone telling you a 400W unit will be sufficient is misleading you. Get a QUALITY 600W+ unit and you won't have to worry about problems down the line. Price differences are absolutely negligible, so getting a 400W unit makes ZERO sense anyways...
You will be absolutely fine! There is definitely a growing tendency to think that you need a psu that is capable of powering several rigs!
Wattage is based on amperage. P = VI, therefore the power a unit can give is equal to the voltage (230V mains) times the current (amperage). BUT from the wattage, you can find the amperage using I = P/V. So saying that you should purchase a PSU based on amperage is nothing more than saying you should purchase a PSU that runs at 230V with the power you require. And since the general public has a greater understanding of power, efficiency and watts, why not categorise them by power, not amperage? Then again, some less trustworthy manufacturers rate their PSUs as the total power that can be drawn from each rail. But in practice, not every rail can be used to 100% at the same time. And this is where PSU lab tests in the CPC mag come in!
There is no need to swap the corsair for a thermaltake. The corsair will handle that rig easily, trust.
Wasting money on a higher wattage PSU when his system will never pull more than 250w makes even less sense.
400W its more than enough. My sig is old and needs updating. But i have a i7 750 running at 3.8Ghz. 6 HDD's, DVD-ROM Drive, ATi 4830, 8GB Ram. And have no problem running my system. If i was to upgrade from here though I would need a bigger PSU. I'd go for a 600W Corsair if/when I do as the GFX cards can pull more power now than they used to.
I assume he means that you should judge it by the amps available on the 12V rail rather than the total wattage (as the 3.3V and 5V rails are very much under-used these days, but the manufacturers still count their maximum theoretical draw towards the total). My power supply gives 25A each on four 12V rails. It seems that manufacturers of other parts are catching on about this misconception, as my graphics card manual stated the minimum amperage of the 12V rail supplying it rather than the minimum wattage of the supply (as I've seen before).
