It is currently Thu Aug 21, 2014 12:50 pm

All times are UTC - 8 hours




Post new topic Reply to topic  [ 15 posts ] 
Author Message
 Post subject: What size PSU and undervolting. P5N7A-VM & Q9400.
PostPosted: Sat Feb 28, 2009 8:14 am 
Offline

Joined: Sat Feb 28, 2009 8:02 am
Posts: 7
Location: England
I just replaced my P4 2.8 which was drawing ~125W @ Idle with something altogether more appropriate:

Asus P5N7A-VM
Intel Q9400
8GB DDR2 800Mhz RAM

I kept my old disks:
2 x 500GB SATA (Samsung HD502IJ)
2 x 80GB IDE

I am pleased to say the least, it is much, much faster and draws much, much less power - ~75W @ Idle. It gets up to about ~125W at load.

Its spends a lot of time idling since its more a server than a PC.

Now to the question. So far I have not swapped the old (bought in 2004) 450W PSU out, I wanted to wait until I knew what power it was drawing and get an 80+ unit.

But what size PSU should I get?

And on a related matter, does anyone have any tips for undervolting with this board and CPU. I would be happy to run it locked at 2GHz if I can get the power down even further.


Top
 Profile  
 
 Post subject:
PostPosted: Sat Feb 28, 2009 2:10 pm 
Offline

Joined: Sat Jan 17, 2009 2:32 pm
Posts: 99
Location: Mexico
quad 9400 is huge for a pc-server!

for an efficient psu, look to PW200 or picopsu150, with AC/DC power brick.


Top
 Profile  
 
 Post subject:
PostPosted: Sat Feb 28, 2009 2:41 pm 
Offline

Joined: Tue Jan 08, 2008 5:09 am
Posts: 397
Location: Copenhagen, Denmark
greenfrank wrote:
quad 9400 is huge for a pc-server!

for an efficient psu, look to PW200 or picopsu150, with AC/DC power brick.

+1!

Swap that quad for a low-power CPU like E5200 or something. Then get a PicoPSU 90W or equal. That will give you by far the best efficiency!

What do you do with this PC that takes a quad anyway?

Cheers!

_________________
Main rig: Antec NSK1380 | Lapped Xeon E3110 | ASUS P5QPL-VM (using IGP) | 2x 2GB Corsair XMS2 800 MHz | MTRON Mobi 3525-32 GB | WD Caviar GP 1TB (Scythe Quiet Driv'ed, on foam) AAM=128 | Lapped Scythe Ninja Rev. A fanless + Arctic Silver 5 | PicoPSU-160-XT + Dell DA-2 200 W brick | M-Audio Audiophile 2492 | 1x Nexus 120 mm @ 550 RPM


Top
 Profile  
 
 Post subject:
PostPosted: Sun Mar 01, 2009 8:20 am 
Offline

Joined: Sat Feb 28, 2009 8:02 am
Posts: 7
Location: England
Well its not a 'typical' home server doling out the occasional mp3 or mpeg file.

Its more a server, based at home.

The P4 with 4Gb had run out of steam, I was going to go E8400 but I really can use all the cores.

Without boring people too much, when I say 'idle' its idling Ubuntu, Solaris, MS Vista, Win2K3 and a few other more transient OE's instances at the same time.

I went Quad core because when I do log into it, either at my desk or from elsewhere I ask it to do a lot and need it to be snappy.


Top
 Profile  
 
 Post subject: Re: What size PSU and undervolting. P5N7A-VM & Q9400.
PostPosted: Mon Mar 02, 2009 1:43 am 
Offline

Joined: Tue Feb 13, 2007 7:28 pm
Posts: 1406
Location: USA
xc wrote:
But what size PSU should I get?

I get get something in the 300-450W range. I don't know about the UK, but in the US there is not much price difference between some 82+ 4XXW models and most 80+ 3XXW models. Hard to say which of these would actually be more efficient at 75W, since this is not within the 20-100% range (that the efficiency rating pertains to) for any of them -- 75WAC on your current PSU is probably well under 60WDC. So, that said, I'd just go with the best price on a trusted brand.

I'd stay away from PicoPSU for this application. Multiple HDD can be troublesome. Getting a brick that can support 100+WDC can be troublesome. You can work around these issues, but I just don't think it's worth the trouble to save 5W (although if you are sure this will be in continuous operation for at > 5 years, it starts to make sense). A fan swap is an easy way to make most PSU silent, if that is a concern.


Top
 Profile  
 
 Post subject:
PostPosted: Mon Mar 02, 2009 1:57 am 
Offline

Joined: Sat Feb 28, 2009 8:02 am
Posts: 7
Location: England
Thanks! I had never considered Fan swaps on PSU's, it seems good advice.

At the moment I am looking at either the HEC Green Earth HEC-350TE which is dirt cheap at £27 or the OCZ 400W ModXStream Pro at £45.

I have never seen the Pico PSU's before, they look a great idea, but not suitable for my application, while I would love to drop an extra 5W (my target was 'a lightbulb') I am hoping undervolting might get me there.


Top
 Profile  
 
 Post subject:
PostPosted: Mon Mar 02, 2009 1:59 am 
Offline

Joined: Sat Feb 28, 2009 8:02 am
Posts: 7
Location: England
I should also ask, why are all the 80+ gold PSU's all in the >800W range?

Is it just easier to get efficiency there or is it that the market segment is larger at that end of the scale.


Top
 Profile  
 
 Post subject:
PostPosted: Mon Mar 02, 2009 12:52 pm 
Offline

Joined: Mon May 08, 2006 4:36 am
Posts: 497
Location: Linköping, Sweden
80+ gold requires 87% efficiency at 20% load, which would be very difficult for a 400W PSU (where 20% is just 80W) while possible for 800W (160W). Plus the fact that you can charge more for a larger PSU makes the investment pay off sooner.


Top
 Profile  
 
 Post subject:
PostPosted: Mon Mar 02, 2009 2:44 pm 
Offline

Joined: Tue Feb 13, 2007 7:28 pm
Posts: 1406
Location: USA
Actually, there are OEM-only < 300W Gold -rated PSU. I wouldn't expect retail versions any time soon, as (floffe correctly noted) it is too hard to charge a price premium at the low Wattages. Basically, at the low Wattages you get what is the most commoditized technology. Right now that is in the 80+ to 82+ level. Eventually, it will get better. If you can't wait and don't mind paying a premium, that is what PicoPSU is for -- it should deliver around 87% efficiency with a good AC-DC brick, even for loads << 50W. Another option would be to wait until vendors like Dell start releasing products based on these OEM-only Gold PSU and just buy the replacement stock from them -- again at a big premium over what you'd expect to pay for a retail model, I'm sure.

One last thing. As consumption gets really low, achieving higher efficiency starts to become fairly useless. If your system idles at 250WAC @80% efficiency, going to 87% efficiency saves you 20W. If your system idles at 40WAC @80%, going to 87% only saves you 3W. Even for an always on application, saving 3W will take a very long time justify the cost of a new PSU.


Top
 Profile  
 
 Post subject:
PostPosted: Thu Mar 05, 2009 6:23 am 
Offline
Friend of SPCR

Joined: Tue Dec 14, 2004 4:06 pm
Posts: 1439
Location: New Hampshire, US
I've got a Q9400, only, I've also got a video card in my system, and a 220W brick with a PicoPSU-120 works just fine. Got the CPU at 3ghz, system draws ~120-130W under CPU load at the wall.

_________________
F@H
Oldest Setup
Old
i5-750 | TR AXP-140 | DFI MI P55-T36 | Lan-Gear mITX | HD5850 | Silverstone ST45SF


Top
 Profile  
 
 Post subject:
PostPosted: Thu Mar 05, 2009 2:59 pm 
Offline

Joined: Tue Feb 13, 2007 7:28 pm
Posts: 1406
Location: USA
ryboto wrote:
I've got a Q9400, only, I've also got a video card in my system, and a 220W brick with a PicoPSU-120 works just fine. Got the CPU at 3ghz, system draws ~120-130W under CPU load at the wall.

But how much did the combo of brick and PicoPSU cost and what modifications did you have to make to the brick to get it to work?


Top
 Profile  
 
 Post subject:
PostPosted: Thu Mar 05, 2009 7:56 pm 
Offline
Friend of SPCR

Joined: Tue Dec 14, 2004 4:06 pm
Posts: 1439
Location: New Hampshire, US
jessekopelman wrote:
ryboto wrote:
I've got a Q9400, only, I've also got a video card in my system, and a 220W brick with a PicoPSU-120 works just fine. Got the CPU at 3ghz, system draws ~120-130W under CPU load at the wall.

But how much did the combo of brick and PicoPSU cost and what modifications did you have to make to the brick to get it to work?


~$70 for the brick and the PicoPSU. I did shorten the brick's power cable, and wired 12v directly to the video card/CPU. But in a file server system, such modifications shouldn't be needed, since you wouldn't have as much draw as I do on the 12v.

_________________
F@H
Oldest Setup
Old
i5-750 | TR AXP-140 | DFI MI P55-T36 | Lan-Gear mITX | HD5850 | Silverstone ST45SF


Top
 Profile  
 
 Post subject:
PostPosted: Fri Mar 06, 2009 3:17 am 
Offline

Joined: Tue Feb 13, 2007 7:28 pm
Posts: 1406
Location: USA
ryboto wrote:
jessekopelman wrote:
ryboto wrote:
I've got a Q9400, only, I've also got a video card in my system, and a 220W brick with a PicoPSU-120 works just fine. Got the CPU at 3ghz, system draws ~120-130W under CPU load at the wall.

But how much did the combo of brick and PicoPSU cost and what modifications did you have to make to the brick to get it to work?


~$70 for the brick and the PicoPSU. I did shorten the brick's power cable, and wired 12v directly to the video card/CPU. But in a file server system, such modifications shouldn't be needed, since you wouldn't have as much draw as I do on the 12v.

What brick was it? 220W with proper plug for 12V PicoPSU is very uncommon.


Top
 Profile  
 
 Post subject:
PostPosted: Fri Mar 06, 2009 5:06 am 
Offline
Friend of SPCR

Joined: Tue Dec 14, 2004 4:06 pm
Posts: 1439
Location: New Hampshire, US
jessekopelman wrote:
ryboto wrote:
jessekopelman wrote:
ryboto wrote:
I've got a Q9400, only, I've also got a video card in my system, and a 220W brick with a PicoPSU-120 works just fine. Got the CPU at 3ghz, system draws ~120-130W under CPU load at the wall.

But how much did the combo of brick and PicoPSU cost and what modifications did you have to make to the brick to get it to work?


~$70 for the brick and the PicoPSU. I did shorten the brick's power cable, and wired 12v directly to the video card/CPU. But in a file server system, such modifications shouldn't be needed, since you wouldn't have as much draw as I do on the 12v.

What brick was it? 220W with proper plug for 12V PicoPSU is very uncommon.


I guess I neglected to mention the plug. I bought a DA-2. I had a 24-20 pin adapter and used that to connect the PicoPSU to the brick's connector. I maybe spent ~10 in additional wires.

_________________
F@H
Oldest Setup
Old
i5-750 | TR AXP-140 | DFI MI P55-T36 | Lan-Gear mITX | HD5850 | Silverstone ST45SF


Top
 Profile  
 
 Post subject:
PostPosted: Tue Mar 17, 2009 6:59 am 
Offline

Joined: Sat Feb 28, 2009 8:02 am
Posts: 7
Location: England
Righty. To wrap this up.

I just installed a OCZ 400SXS (Stealth Extreme). I know this is only 80+ (not bronze, silver or gold) and my system sits well under 20% of its load, but it was on offer so i went for it.

The system now draws 65W. A saving of about 10W or a saving of ~13% compared to the old PSU.

This puts my system only 6W over my target of 60W.

Its not going to get any lower for me, I suppose I could disconnect the two fans on the front of the case and maybe get to 60W if I was so inclined, but I wont.

All in all I am blown away that my geekbench score has gone up by ~300% and my power consumption down by 50% compared to my old P4.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 15 posts ] 

All times are UTC - 8 hours


Who is online

Users browsing this forum: No registered users and 1 guest


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group