7800gt SLI and Fortron 450W PSU

[keidanny]

is the psu good enough to power the rig in my sig with the addition of another 7800gt in sli and possible 2 more SATA HDs?

Thanks!

 

[Wentelteefje]

Hmm, it could get tricky... For your safety, I'd advise you to take something slightly heavier... I'm not saying that it will instantly blow, but when running dual 7800GTs, a couple of hard disks and an OCed Opteron, your PSU will be stressed a lot...

 

[keidanny]

yeah that's what i was affraid of.. i was hoping for someone else to have a some-what similiar rig that's tried it first. anyone else have any input? thanks a lot!

 

[Allio]

I quickly ran your system through the PSU draw calculator here, and at full draw with those extra SATA drives you're looking at over 550 watts. A dual core opteron at 2.7ghz (holy crap, by the way) apparently pulls nearly 200 watts by itself, and the two video cards could easily do 220 watts if you keep that overclock. Obviously that's a worst case scenario with everything in your system going at once, but you don't really want to flirt with danger on these matters. I don't think a decent quality 600w PSU would be wasted on your system if you plan to make those upgrades.

 

[CP5670]

That thing is not very accurate about the processors. All the dual cores for example have the same power usage listed, regardless of their speed.

It seems 7800GTs don't actually use all that much power. They're only a little more than a single 512MB GTX according to Techreport. That power supply may just barely be enough, but I don't think you will be able to add the extra hard drives in addition to the second GT.

 

[keidanny]

oo thanks for all your help everyone. now time to find a nice psu.. hehe

 

[BW86]

Thats plenty of power. PLENTY.

 

[ElFenix]

Originally posted by: keidanny
is the psu good enough to power the rig in my sig with the addition of another 7800gt in sli and possible 2 more SATA HDs?

Thanks!

anand's uber gaming rig with the latest FX processor and a not very efficient OCZ powerstream pulls down less than 300 watts from the wall at peak usage. i think the fortron will take your system with ease

 

[Matt2]

System in sig. My 500w Fortron handles the SLI no problem.

I'm not sure about the 450w Fortron, but my 500w is not really 500w, it's really 460w. I think you'll be ok.

 

[DeathReborn]

The rig in my sig at 100% PSU Utilisation pulls roughly 464W so you should really be looking at 500W+ Peak Power & 480W sustained output. I myself use a Hiper Type-R 580W Modular PSU that has a Peak Power Output of 630W.

I dunno what the peak output on that Fortron is but I supsect its somewhere around 500W.

 

[keidanny]

wow mixed thoughts all around.. very interesting.

@Matt2: how (or why?) do you know your 500w runs at 460w?

@DeathReborn: How did you calculuate PSU Utilisation?

Thanks again!

 

[DeathReborn]

Originally posted by: keidanny
wow mixed thoughts all around.. very interesting.

@Matt2: how (or why?) do you know your 500w runs at 460w?

@DeathReborn: How did you calculuate PSU Utilisation?

Thanks again!

Using the link that Allio posted (http://extreme.outervision.com/index.jsp) I calculated the power draw at 100% utilisation and it came up at 464W. I have left it running several tests overnight and it never went over 437W. Of course your Dual Core opteron will draw probably 30-40W more than my 3500+ Venice quite easily.

 

[slash196]

The 7800GT actually pulls less power than the 6800 series. I think you'll be fine (because in all likelyhood you'll upgrade your current graphics card rather than add another one in the future). However, 500 watts is a nice round number, and Fortron makes a fine PSU by the name of the Blue Storm. Its kept the rig in my sig running with no complaints for going on a year now.

 

[yhelothar]

Your computer will NEVER get to 100% utilization. Heck even 80% is a stretch. I bought one of those Kill-a-watt thingys from ebay. That site says my computer draws 399W at 100% utilization. The kill-a-watt measures 80W idle, and 125W full load.

 

[Wentelteefje]

The "problem" is that, when I'm right, your Fortron 450W is actually a 400W with a peak output of 450W... I recall someone stating this... If that's the case, and you have to run your system with a 400W PSU, then I would get worried... If it had some 450W on its own, things would probably still work out...

I'd rather be sure about my PSU instead of taking my chances... Modern systems do draw a lot of power...

EDIT: Anand's test system with the FX-55 (which should draw 104W) and SLI 7800GTs makes up for a total power draw of 316W... Consider the fact that his overclocked Opteron draws 220W (according to this) and his comp will have more hard disks, I would say it doesn't seem quite useless to look around for another PSU...