How much will a 300w power supply run?

PSUs: The source of DC power for all components in the PC & often a big noise source.

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Post by davidstone28 » Thu May 18, 2006 1:15 am

Silverstone ST30NF 300W passive PSU (European version):-

- Athon64 3200+ (Venice core) overclocked from 2.0ghz to 2.6ghz @ 1.4v
- Nvidia Geforce 7900GT (overclocked from 450/1320 to 570/1600)
- Asus A8N SLI Premium motherboard
- 2 x 512mb DDR DIMMs @ 2.8v (Crucial Ballistix)
- Creative Audigy 2 (PCI)
- 2 x 120mm Antec tricool fans on lowest settings
- 2 x 120mm Nexus fans
- 3.5" fan controller connecting all fans with fan control set to 50%
- 1 x 250gb Samsung P120 PATA HDD
- 1 x 160gb Samsung P80 SATA HDD
- 1 x 200gb external Samsung P120 PATA HDD connected using USB2.0 only
- 2 x optical drives (DVD-RW and CD-RW)
- 1 x USB keyboard (Logitech DiNovo)
- 1 x USB mouse (Logitech MX610)
- Cool 'n Quiet disabled

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Post by mathew7 » Tue Jun 20, 2006 4:00 am

This is not about PSU, but about power draw.
When I bought an APC backUPS 350 (which was 350VA and 210W) I had the following system:
P4 Northwood at 2.4GHz
Abit IS7
Thermaltake 480W PSU (I don't remember what model)
Gigabyte Geforce 5900XT
Creative Audigy
2xSeagate 7200.7 80GB HDDs
LG 19" CRT (I don't remember if it was connected to battery backup).

When I played games (at 1024x768) I had no problems.
But when I played with the CPU overclocked to 3GHz (FSB250) and the geforce overclocked a little (about 10%), the APC unit started to beep with "overloaded condition". That would be more than 210W (if I left APC power chute open in background, I would see right after exiting the game around 230W). However I don't remember if the monitor was pluged into the "surge-only" socket or "battery backup" socket. It draws about 60W at 1024x768. I have switched to the 600VA APC model.
I don't know my current system's peak power draw, but I can get to 120W at idle (with LCD and only 1 HDD).

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Post by Devonavar » Tue Jun 20, 2006 9:13 am

If you switch to a PSU with active PFC, your UPS should be able to support almost 350W output, which is more than enough to compensate for your overclocking attemps.

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Post by dhanson865 » Tue Jun 20, 2006 6:38 pm

on a 325 VA, 185 Watts UPS I'm running a

Seasonic 400W Tornado A3
Athlon XP 1700+ overclocked to about 1.75 GHz reports as a 2100+
Volcano 7 HS/FAN
5 case fans (80mm mix of TOPOWER and Nexus)
2 hard drives (PATA 7200 RPM 8MB cache)
768MB ram (3 x 256 all doublesided sticks) running at around 140 MHz

The monitor was NOT on the UPS.

The UPS lasted just under 2 minutes (about 113 seconds) with a few web browsers open and an online 2D game keeping CPU activity around 10 to 30%.

According to APC the Typical Backup Time at Half Load is 8.1 minutes (92.5 Watts) and at Full Load it is 1.0 minutes (185 Watts)

If my guestimation is right that puts my draw on the UPS for that test in the 130-150W area.

I used to run basically the same components (minus some ram) on the stock Antec power supply which was a 300W unit PP-303XP with no problems.

I just went to the Seasonic to save on noise/electric costs. I live in the south so waste heat leads to air conditioning more than half the year.

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Post by mathew7 » Wed Jun 21, 2006 10:48 am

I have just played a little Oblivion on my system (see sig, except with just 1 160GB HDD connected). With 1280x1024, 4xAA and no vsync, my APC unit reports 192W (it's USB interface is connected to my father's laptop). And this is my AC power draw (including ~30W for my LCD). So i would say that even with a dualcore AMD with 7800GT (which consumes more power than 7900GT), a good 300W PS would be enough. For GTXs and/or SLI, 400W is still enough. So maybe I sould look to change my Phantom 500 with a Phantom 350 :)
BTW: Antec Phantoms do not have active-PFC.
I would like to try also a Thermaltake 480W PSU (with APFC) which I have and some overclocking results. When I do it, i will post you the results.

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Post by xxkrnxstylezxx » Wed Jun 21, 2006 11:13 am

Hey guys, I'm trying to decide whether I need a new PSU or not. Maybe you can help me out...

Right now, I have a Seasonic Super Tornado 350watt revision A.3.

And these are my specs.

AMD 64 3000+ Winchester
Zalman 7000B HSF
2 x 1GB Corsair XMS PC3200
Evga Nforce4 SLI motherboard
Evga 7800GT CO
Seagate 7200.7 160GB IDE
Maxtor DM10 200GB IDE
Audigy 2 ZS
Zalman MFC1 fan controller
2 x 120mm Globe fans
Logitech MX duo
Logitech MX1000
Logitech G7

And I think that's it. The reason I ask is that I've been having random freezing problem in games. I'm not sure if the video card is faulty, or I'm just lacking power. I figured it was time for me to upgrade my PSU. However, I used to have an X800XT and 1GB ram with the above specs, and it ran perfectly.

So...a bit confused.


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Post by jaganath » Wed Jun 21, 2006 12:05 pm

You shouldn't be having any problems with that setup, power-wise:

And what about GeForce 7800 GT?

Since the market our today’s hero is targeted at is much more sensitive to the PC component pricing, it would be very logical to suppose that the system intended for NVIDIA GeForce 7800 GT is less likely to have a pricy and powerful PSU. According to NVIDIA, GeForce 7800 GT requires a 350W power supply unit, which is not an extraordinary specification nowadays.

While generally our power consumption measurements are very precise, this time we would recommend to consider them cautiously, as NVIDIA GeForce 7800 GT graphics card behaved very strangely during the measurements. Our multimeter, indicated that the graphics card consumes nearly nothing from 3.3V lines (about 2.1W), which is something that we see for the first time. Still, power consumption of approximately 57W seems to be correct, as the GeForce 7800 GTX that has more pixel and vertex pipelines enabled and operates at higher clock-speeds consumes about 80W.
Could be a flaky video card?

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Post by Bar81 » Wed Jun 21, 2006 10:42 pm

xxkrnxstylezxx wrote:
And I think that's it. The reason I ask is that I've been having random freezing problem in games. I'm not sure if the video card is faulty, or I'm just lacking power. I figured it was time for me to upgrade my PSU. However, I used to have an X800XT and 1GB ram with the above specs, and it ran perfectly.

Welcome to nVidia AIB "quality". It's a poorly kept secret that all of these OC nVidia cards are dying/flaking out due to the OC. Try putting the speeds of your card at nVidia's stock settings and see if you have freezing. If you don't it's RMA time. Either way, I would RMA the vid card.

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Post by mexell » Sat Jun 24, 2006 12:06 pm

Now for mine:

I have a beQuiet (very famous in Germany) 380W PSU with:

- A64 Venice 3200+ 2.0 GHz
- 2x PATA Hdd (Samsung, 160GB, WD, 120GB)
- 1x SATA Hdd (Maxtor? 200GB)
- XFX GF 7600GS (planning to get a second one)
- 2x Kingston DDR333 512MB (old remains, still unchanged, but working)
- DVD burner, DVD-ROM
- 2x Papst 80mm, 2x Arctic Cooling 80mm (w/ TC)

Plans for the future are:

- go get an Antec P180
- throw all the 80's in trash and get an additional 120 (I think nexus or papst) for cooling of the SLI rig
- go get a second GF7600GS, as it is completely passively cooled and offers all the fancy new graphics effects such as HDR with only <30W peak power consumption - but it's too slow alone;)

Do you think my PSU will let me do this? It's a bit older (about 3 years), but it's known as a very stable and reliable one.


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Post by SD-Plissken » Sun Jul 23, 2006 2:04 pm

[*]PSU: Silverstone SST-ST365
[*]CPU: Opteron 148 @ 2.8
[*]Cooling: Scythe Ninja
[*]MB: BioStar T-Force 939
[*]RAM: 1.5GB (2x 512 MB) Infineon (2x256) Kingston HyperX DDR 400
[*]GFX: Geforce 6100
[*]DVD: Nec ND-3550A
[*]HD1: Samsung MP0402H 40GB
[*]HD2 : WD800JD SATA-80GB
[*]HD3 : WD2500YS SATA-250GB
[*]1x120mm Rear Fan
Last edited by SD-Plissken on Fri Apr 06, 2007 6:20 am, edited 1 time in total.

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Post by Goldenhorde » Mon Jul 24, 2006 1:00 pm

I want to know if my psu can handle
cranking my cpu core voltage from 1.62 to
the next quantom leap for a faster cpu
iev had it a 2010 stable

modified front case fan cut big round hole
for the cup holder to do a wind tunnel
affect for my second psu :wink:
MSI KT266 Pro2-U with a XP2000 @ 1759 1.62 at 37c
Geforce 4 mmx 64 SE fast but no pixil so crap
Clocked at 287/332
with a 12v slot fan
Two 52 24 52x cdwrighters
256x2 ddr333 and a ddr400
ultimit hardrive cooler with nothing in it just cold air pushed through 2 fans
Lazy boy Chair
1 hardrive partitioned too 4 drives
bios update
eight fans all up
air conditioning New Zealand New
A very hard to get saitek p880
Mitsubishi TV via Sharp x380 super speed rewind vcr via Tv out
Dell 15inch 120hurtz monitor through 230W Tv cabnet mounted AT POWER SUPPLY UNIT
Cap Card for decoading sky
300 W PSU
468kbps broardband flatrate

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Post by Bar81 » Fri Sep 15, 2006 12:54 pm

Update. Here's what I've got so far on my Silverstone SST-30NF fanless 300W:

Opteron 170 @ 2.7Ghz (270x10) [1.44v]
2x 1024MB Mushkin Redline XP4000 @ 270mhz (1350 HTT) [2.8v]
Sapphire A9RD580 PURE Crossfire [1.22v all around]
ATI X1800 XL @ 550/650
Terratec DMX 6fire 24/96 with Roland SCB-55 MIDI (breakout box)
JMicron JMB360 PCI-E x1 eSATA
Western Digital WD740GD Raptor
2x Western Digital SE16 500GB (RAID1)
2x Maxtor MaxLine III 300GB (RAID1)
Maxtor Diamondmax 10 250GB in IEEE1394 enclosure
Western Digital SE16 500GB in eSATA enclosure
4x120mm Nexus fanmated at <1000 rpm
Logitech G5 Laser Mouse
BenQ 1640B DVD-RW

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Post by BrianE » Sat Sep 16, 2006 7:37 pm


Well, not that this system is any more demanding than Bar81's monster ;) but here's what I've been running for a while, just to add a new/different power supply to the ones already mentioned:

Fortron FSP FSP300-60THN

A64 2800+ Newcastle (130nm) @ stock 1.8Ghz with CnQ only
Asus K8V-MX
2x 512MB Corsair/Samsung generic memory
Powercolor X800 Pro 256mb AGP (stock Mhz)
80GB Maxtor 7200RPM (forget the model)
DVD burner
80mm Coolermaster fan (Speedfan controlled)
2x 80mm slot fan (temporary)
LED light bar and Coolermaster Musketeer :mrgreen:

This is a medium-ish power gaming rig that has run 100% stable so far. I have been really impressed with the noise characteristics of this power supply considering it cost less than $40. Even undervolted, the lousy slot fan makes more noise than the PSU, which I haven't heard ramp up yet.

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Post by Edward Ng » Sun Sep 17, 2006 6:08 pm

My new machine is as follows:

Seasonic SS-300 (yes, 20-pin PSU), fanmodded and grille removed
Antec SLK2600, front lower openings sealed up, one Nexus 120mm silent fan out back
ASUStek P5B Deluxe
Core 2 Duo E6600
Thermalright SI-128, fanless
one 7600GT 256, fanless
one 6600 256, fanless
one 100GB 7200rpm Seagate SATA 2.5" drive, inside a SilentDrive
one 80GB 5400rpm Western Digital PATA 2.5" drive, inside a SilentDrive
Plextor PATA slot loading dual layer DVD burner
Echo Audio Mia MIDI

Can't hear it from halfway across the room, CPU spends most of its time in the upper 40s to low 60s (heavy load) and chipset stays in the low 50s to mid 60s. Stock CPU speed, stock voltage (can't undervolt it, even on latest BIOS, although I can reduce the multiplier from stock--cannot raise it from stock). Flawless operation; spends its time handling Outlook 2003, Trillian, Photoshop CS2, foobar2000 and WoW.

EDIT: The reason for the dual video cards is my trihead setup.


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Post by Bar81 » Sat Sep 23, 2006 9:45 am

BrianE wrote::shock:

Well, not that this system is any more demanding than Bar81's monster ;)
Yeah, I'm running on 110v and this PSU is supposed to be only 250W at that voltage. I know it's running well over 315W as my APC UPS handles up to 315W and it hits that with the vid card at stock (warning bells going nuts but everything still runs flawlessly - looks like I have to get a new UPS that can handle this PSU :) ). I have a sub 1k rpm 120mm Nexus fan blowing on it and that's it. Looks like Silverstone wasn't lying when they said the actual unit is really 400W+ but without the fan.

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Post by Devonavar » Sat Sep 23, 2006 12:07 pm

Keep in mind that the 315W number is not the same at the wattage output of the power supply. According to our test, the PSU is ~80% efficient at full load. Assuming that the wattage consumed by the power supply is actually 315W, the true output would be about 315W x 0.80 = 250W ... right around the maximum capacity. You're looking at input, not output. Power supplies are rated by output, the input will always be higher due to efficiency losses in the power supply itself.

Also, wattage ratings on UPS units are unreliable, because the ratings make an assumption about the power factor of the system that it is powering. Your fanless Silverstone has active PFC, which not typical, and makes the wattage rating meaningless. You need to look at the VA rating for a more accurate idea of how much power the UPS can handle before complaining.

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Post by Bar81 » Sun Sep 24, 2006 3:03 am

Thanks for the clarification.

APC claims the UPS is 500VA. What would that mean?

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Post by burebista » Sun Sep 24, 2006 3:33 am

Usually, 500VA x 0.6 PF coefficient = 300W output

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Post by Bar81 » Sun Sep 24, 2006 7:10 am

Interesting. This is the exact model: ... _watts=200

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Post by Devonavar » Sun Sep 24, 2006 11:22 am

But, your power supply has active PFC, which means that you're more likely to see 500VA x ~0.98 PF = ~496W. I'd be shocked if your system is drawing that much power... and I would expect your PSU to shut down long before then.

Perhaps you're right, the alarm is tripping around ~315W. It just doesn't make sense to me given the way UPS units work. If you're really curious, pick up a Seasonic Power Angel or a Kill-a-Watt and measure the power directly...

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Post by Bar81 » Sun Sep 24, 2006 10:25 pm

That's a good idea. Will probably do so when I go back to the US during Christmas (as well as an unpgraded UPS). Thanks for all the info.

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Post by jreiter » Mon Sep 25, 2006 2:13 am

Although I do have a very large power supply, I wanted to post here as my actual power usage falls substantially under 300 watts. (My huge power supply is obviously unnecessary.) Power measurements were taken with only my computer (nothing else) plugged into a Kill-A-Watt meter. My power readings are:

Idle (CnQ enabled): 128 watts/204 volt-amps
Full load: 250 watts/370 volt-amps

My machine specs are:

Antec TruePower 2.0 550W psu
Antec P180 case
2x Antec Tri-Cool fans @ low speed
Asus A8N-SLI mobo
- stock Northbridge fan (can't replace it)
Nvidia 7800GT (overclocked @ 470/1.10)
- Arctic Cooling cooler
AMD Athlon64 3800+ Venice (overclocked @ 2.6, overvolted)
- stock heatsink/fan (surprisingly quiet)
2x OCZ ram, 512M each (overclocked, overvolted)
3WARE 7500-4 pci raid card, RAID5 mode
4x Hitachi HDS722516VLAT80 drives, 160G each
IBM 16G drive (for misc test installs, usually off)
Plextor DVD-RW drive
Soundblaster Audigy pci card
Echo Gina24 pci card (plus external break-out box)
Logitech G15 keyboard
Logitech MX518 mouse

As you can see, this is a fairly heavily configured system with overclocking, 5 hard drives, and a full complement of expansion cards. In the past I was actually running a pair of 6800GT video cards (overclocked) in SLI mode, so that would've kicked up the power usage a lot more. That's why I initially bought such a large power supply. To be honest, it appears a high quality 400w psu probably would've been fine as long as the individual 12v rails could each support a high end, overclocked video card. Now days, though, a much smaller psu would do just fine with my single video card.

Maximum machine load was generated by running various combinations of benchmarks, stress tests, and applications/games until I found the combo which generated the highest power consumption. If anyone's interested, the final combo that generated the most load was 3Dmark06 + Prime95 (in-place large FFT test). Most combos came close, but this combo edged out the others by just a few watts.
Last edited by jreiter on Tue Sep 26, 2006 8:57 am, edited 1 time in total.

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Post by Owen1978 » Tue Sep 26, 2006 7:18 am

Reading this thread just makes you laugh at people who go out an buy 600W+ psu's when they are running less than what some of the guys on here have

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Post by Bigg » Tue Sep 26, 2006 8:37 am

I used to have a huge system running off of a Seasonic Super Tornado 300W PSU.

It had:
Abit IC7-MAX3
P4 2.4C
1GB Corsair XMS
2x Seagate 120GB RAID 0
Maxtor 40GB
10 Fans

It worked just fine. The 3rd HDD, CD-ROM, and 2 fans have since been removed for noise reasons, the CD-RW doesn't work (never bothered to remove it) and I use a fan controller to keep the noise down. The fan controller has one of those silly cold cathode lights, and it works just fine. Unless you have a totally over the top system, you DON'T need more than 300 Watts of power. If you need more than 300 watts of power, your system is probably going to sound like a 747 from the cooling to get rid of that heat, so you have to look at a PSU porblem from the angle that a 300W output is a given, and the system has to be contructed to work well with a 300W PSU. Heck, the iMac uses like 40 watts, and it is a powerful system with a monitor and everything.

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Post by merlin » Tue Sep 26, 2006 11:45 am

Since my Aria obviously runs a 300 watt psu, might as well post what it's running. The following is easily run with plenty of headroom:

Socket A Sempron 2400+ oced to 2ghz(no voltage change)
MSI Microatx Nforce 2 IGP
PNY Geforce 6600 oced about 10% 256MB
2 HD's
4 Fans
Onboard sound

I haven't done any formal testing, but it seems at most this system draws around 100-110 watts.

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Post by jreiter » Tue Sep 26, 2006 12:18 pm

Does anyone else here use any sort of power meter? You can pick those Kill-A-Watt meters up on the net for relatively cheap (around $30 or so). I'd highly recommend it. It'll tell you exactly how much power your system is actually pulling, plus you can use it on other stuff around your house to see what the worst offenders are as far as power consumption.

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Post by disphenoidal » Thu Sep 28, 2006 3:17 pm

Generic FSP 300W unit with undervolted Panaflo running:

Sempron 2800 overvolted and OC'd from 1.6 GHz to 2.2GHz
Radeon 9550 overclocked to 9600 Pro clocks
80 GB drive
400 GB drive
2 sticks 512MB DDR-DRAM
Optical drive

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Post by DArtagnan » Thu Sep 28, 2006 4:25 pm

Although I do not have a 300 Watt power supply, I figure that someone might find this useful.

Silenx 400 Watt active PFC (I know, a hated brand, but I bought it before I read about the brand here, and I must say, it is very quiet)

Core 2 Duo 6600
Asus 5PB Deluxe
7900 GTX
2 GB Crucial Ballistix memory DDR2 800
Samsung SP2004C
DVD Burner
DVD Player
3 undervolted nexus fans (2 case 1 CPU)

I was woried about using my 400W psu from my old computer, but it has worked flawlessly in this higher power draw newer computer

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Post by jreiter » Thu Sep 28, 2006 4:38 pm

DArtagnan, your new machine actually looks to be a pretty low-power setup compared to many older machines. Here are a few power-saving items on your machine:

1) The 7900 series Nvidia cards are lower power than most of their previous high end cards since they use a smaller process chip.

2) The new Core/Core 2 CPUs are very low power. Much lower power than the P4 series.

3) DDR2 is lower power than DDR.

I'd be surprised if your machine even consumes 250 watts at peak when fully loaded. 200 watts or so is probably your peak, with maybe 100w idle (or less). Yay for new technologies! :)

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Post by fabre » Thu Nov 23, 2006 3:55 pm

on a 330w Seasonic S12 I run

- 1 x Athlon 64 X2 3800,
- 2 x 512 DDR PC3200
- 2 x WD2500KS
- 1 x ATI X800 XT PE
- 1 x Firewire pci card
- 1 x DVD Writer
- 1 x Floppy
- 2 x 120mm (5V)
- 1 x 92mm

Probably should also mentioned the USB fed peripherals:
- 1 x webcam
- 1 x Scanner
- 1 x Steering wheel w/ pedals
- 1 x compact flash reader

Probably will need to upgrade the psu the day I add more ram and a new video card.

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