Sufficient PSU?

[matt80]

Hi,
I've currently got a 400W Antec PSU that I've had for 2-3 years. I am upgrading my system to the following:

Intel Pentium D 820 CPU
Intel 955XBK Mobo
nVidia 7900GT (or ATI equivalent - not decided yet)
40GB Maxtor IDE HDD
DVD-ROM
CD-RW
Floppy drive

Is my current PSU sufficient? I've tried that PSU calculator thingy, but to be honest I don't understand half the questions it asks

 

[matt80]

Oh, and a couple of case fans

 

[HPTech]

Personally, I would look for a better PSU to go with that rig, the power draw on the 805's when overclocking is insane, and running the high-end cards as well you want lots of stable power.

MikeHP

 

[matt80]

As a matter of interest, what is the consequence of an inadequate PSU? Will it just cut out when under heavy load?

 

[Henny]

Wattage is nearly meaningless. You need to compare amperage capacity from each rail vs. your estimated consumption. (+12v rail is usually the critical supply).

Their are plenty of PSU calculators out there to give you a better idea.

I wish PSU manufacturers wouldn't even specify wattage.

 

[pkme2]

http://www.psuinquisitor.com/ is a start.
My preference is either Enermax/Seasonic.

 

[zagood]

Bad PSU can fry components. Mediocre PSU can keep you from a good overclock but keep your system stable at stock. Decent PSU makes you not fear hearing a "pop" and then seeing a blackscreen, can also be much more quiet. Excellent PSU automatically makes you an expert on these forums (or so it seems...)

Safe bet is always a new PSU. Post the specs from the side of the PSU though when you get a chance...open your case and look at the sticker on the PSU housing. Model number, and those numbers in the grid...most importantly the +12v rating.

-z

 

[acegazda]

like someone said, don't look at wattage, look at the amps on the 12v rails. Enermax and seasonic usually have around 32amps combined (you can't just add both of them up) and thats enough to run SLi. The seasonics generally run quietest, but they're also the most expensive. For my purposes (and yours if your overclocking) go witht the seasonic. 400w should do it. Anyone correct me if i'm wrong.

 

[acegazda]

correction: Seems like the 12v rails on the seasonic only do 15amps and 14amps anyone know the combined wattage? Also it isn't available in 400w, just 430w.

 

[Zepper]

You probably don't need more total wattage than 450 or so, but as mentioned above, you may need to get a PSU with the power allocated more to the +12 rail. One of those load calculators may be helpful in getting a ballpark number.

.bh.

 

[JEDIYoda]

Originally posted by: acegazda
correction: Seems like the 12v rails on the seasonic only do 15amps and 14amps anyone know the combined wattage? Also it isn't available in 400w, just 430w.

You don`t need to have seperate rails....

 

[acegazda]

so what is the combined ampage? JhonnyGuru gave it a less than gracious review.

 

[pkme2]

Found some great prices on Seasonic's
http://www.xoxide.com/seasonic.html?gclid=CILB1rXOqoUCFTV7JAodDwtd3Q

If one wants quiet. here's 3!

 

[FelixDeCat]

Originally posted by: JEDIYoda

Originally posted by: acegazda
correction: Seems like the 12v rails on the seasonic only do 15amps and 14amps anyone know the combined wattage? Also it isn't available in 400w, just 430w.

You don`t need to have seperate rails....

Thats true, but it wouldnt hurt either.

 

[Zepper]

felix,
Split rails are another yet another bright idea brought to you by your friends at Intel - whatever happened to BTX anyway... :roll: They don't even adhere to their own ATX spec that codified split rails any more. Single rail is much more flexible.

.bh.

 

[TrevorRC]

Originally posted by: FelixDeKat

Originally posted by: JEDIYoda

Originally posted by: acegazda
correction: Seems like the 12v rails on the seasonic only do 15amps and 14amps anyone know the combined wattage? Also it isn't available in 400w, just 430w.

You don`t need to have seperate rails....

Thats true, but it wouldnt hurt either.

Split rails do hurt; because you can't use all of the amperage allotted to you.
2 rails of 15A each.
If Rail 1 uses 10A; and has 5 left to spare, rail 2 may need 20...but it's capped @ 15.
So, you've got 5A sitting there that you can't use. The total necessary amperage is there, but it can't be utilized. Hence why a lot of power supplies that 'Look strong enough' can't handle present-day graphics cards, especially with SLi systems.

Mind you, you don't have cheap MOSFETs/transistors blowing up on you, but if you spend a few more dollars that isn't a problem. [Jonny said somewhere, transistors that can handle more than 30A without blowing up sporadically are a bit more expensive than those that aren't, and that's why the multi-rail standard was created. For consumer health. ]
--Trevor