Underloading a PSU?

Randy P · Jun 27, 2008, 09:37 PM

Is it possible to have a PSU that's simply too powerful? I've been Googling for a while and can't seem to see any info that says this is a possibility. Any of you guys know? One of DH's Members suggested it was possible that a PSU that isn't working very hard can actually 'wank' your pc in some way...stability, mess the mobo; etcetera.

Just looking for some confirmation one way or the other. Thanks in advance as always.

procupine14 · Jun 27, 2008, 09:43 PM

I have heard of this happening if the PSU is excessively huge and the system doesn't draw very much power. Some PSUs are actually stated that they prevent stability issues when it is under a very light load. example: if you have an 800W PSU and your system is only using 250W you could run into stability issues due to the fact that there is only a 31% load on a PSU that is engineered for a load of at least half of its capacity.

Yes I have heard of this but I have never experienced this due to the fact that i buy PSUs according to the demands of the systems that they are going into

OldBuzzard · Jun 27, 2008, 10:20 PM

Actually, even tho I used the term UNDERLOADING, it would properly be called CROSS LOADING.

Try doing a google search for: PSU "CROSS LOADING"

Matth · Jun 28, 2008, 10:55 PM

Where "minimum load" is specified, it is usually quite small, after all, even high power systems on high power PSUs, can be running with the processor in minimum operating state, the graphics drawing only idle power and the hard disks in spindown.

Most tests seem to take the PSU at 25%, 50%, 75% and 100% loads, but the cross loading charts sometimes show that voltages could move out of specification under certain loading patterns.

Randy P · Jun 29, 2008, 12:20 AM

Well, after doing some extra research it seems that this possibility is incredible unlikely; not impossible, but very very rare. I think I just have a wanky mobo - simple as that.

mkk · Jun 29, 2008, 05:39 AM

Another thing that can happen is that the powersupply might not run very efficiently at a load very low compared to its maximum, but still just wasting some electrical power rather than causing any problems. An increasing number of 80 PLUS certified products are efficient over the major part of their capacity range, but quite a few others are still only reaching good efficiency numbers when loaded around half of their full capacity and above.

Randy P · Jun 30, 2008, 10:33 PM

Thx for all the input guys. One thing's for sure and that's I'm getting rid of the thermaltake express. Again much thx guys!

Jun 27, 2008, 09:37 PM	#1
Randy P HardwareHeaven Senior Member Join Date: Nov 2004 Location: Canada Posts: 489 Rep Power: 49 System Specs	Underloading a PSU? Is it possible to have a PSU that's simply too powerful? I've been Googling for a while and can't seem to see any info that says this is a possibility. Any of you guys know? One of DH's Members suggested it was possible that a PSU that isn't working very hard can actually 'wank' your pc in some way...stability, mess the mobo; etcetera. Just looking for some confirmation one way or the other. Thanks in advance as always. __________________ You only go this way once.

Jun 27, 2008, 09:43 PM	#2
procupine14 Why is it Beeping!?!?! Join Date: Apr 2007 Location: USA, Missouri Posts: 1,400 Rep Power: 58 System Specs	I have heard of this happening if the PSU is excessively huge and the system doesn't draw very much power. Some PSUs are actually stated that they prevent stability issues when it is under a very light load. example: if you have an 800W PSU and your system is only using 250W you could run into stability issues due to the fact that there is only a 31% load on a PSU that is engineered for a load of at least half of its capacity. Yes I have heard of this but I have never experienced this due to the fact that i buy PSUs according to the demands of the systems that they are going into __________________ HTPC/file server: Windows 7 Ultimate 64-bit - AMD Phenom x4 9850 - 4GB OCZ DDR2 800 (2x2GB) - 1TB WD Black - 4 x 1TB Hitachi DeskStar in RAID 5 - ATi TV Wonder Digital Cable Tuner - HIS Raedon 4850 512MB - ASRock N68C-S UCC mobo - OCZ ModExtreme Pro 500W PSU GF's Gaming PC: Windows 7 Ultimate 64-bit - AMD Phenom 9850 - 4GB OCZ DDR2 1066 - 500GB Western Digital GP - HIS Raedon 5770 1GB - ASUS M3A78-EM - Zalman 650W PSU Media Streamer: Win 7 Pro 64-bit - AMD Athlon x2 3200+ - 4GB SuperTalent DDR2 800 - 250GB SeaGate Barracuda - MSI K9N6PGM2-V2 - ASUS Raedon 5450 SILENT - FSP group 250W PSU

Jun 27, 2008, 10:20 PM	#3
OldBuzzard DH's oldest Geek Join Date: May 2003 Location: Oberlin, OH Posts: 2,783 Rep Power: 145 System Specs	Actually, even tho I used the term UNDERLOADING, it would properly be called CROSS LOADING. Try doing a google search for: PSU "CROSS LOADING" __________________ When looking for a reason as to why things go wrong, never rule out sheer STUPIDITY

Jun 28, 2008, 10:55 PM	#4
Matth Flash Banner Hater Join Date: Jun 2002 Location: UK Posts: 3,426 Rep Power: 93 System Specs	Where "minimum load" is specified, it is usually quite small, after all, even high power systems on high power PSUs, can be running with the processor in minimum operating state, the graphics drawing only idle power and the hard disks in spindown. Most tests seem to take the PSU at 25%, 50%, 75% and 100% loads, but the cross loading charts sometimes show that voltages could move out of specification under certain loading patterns. __________________ Mary had a little lamb, Her father shot it dead Now Mary takes her lamb to school, Between two crusts of bread

Jun 29, 2008, 12:20 AM	Thread Starter #5
Randy P HardwareHeaven Senior Member Join Date: Nov 2004 Location: Canada Posts: 489 Rep Power: 49 System Specs	Well, after doing some extra research it seems that this possibility is incredible unlikely; not impossible, but very very rare. I think I just have a wanky mobo - simple as that. __________________ You only go this way once.

Jun 29, 2008, 05:39 AM	#6
mkk Cthulhu/Dagon 2012 Join Date: Oct 2003 Location: Gefle, Sweden Posts: 4,490 Rep Power: 132 System Specs	Another thing that can happen is that the powersupply might not run very efficiently at a load very low compared to its maximum, but still just wasting some electrical power rather than causing any problems. An increasing number of 80 PLUS certified products are efficient over the major part of their capacity range, but quite a few others are still only reaching good efficiency numbers when loaded around half of their full capacity and above.

Jun 30, 2008, 10:33 PM	Thread Starter #7
Randy P HardwareHeaven Senior Member Join Date: Nov 2004 Location: Canada Posts: 489 Rep Power: 49 System Specs	Thx for all the input guys. One thing's for sure and that's I'm getting rid of the thermaltake express. Again much thx guys! __________________ You only go this way once.