Member Avatar for ReverseC

I will be upgrading my computer with a new CPU and a few more DIMMS and I was curious if you guys think I should get a 'juicier' power supply. The CPU I'm looking at will increase my watts used by 23 watts. See the before and after specs below.

Current HW & Sys Specs
Power Supply - Allied AL-A350 ATX 350W
MoBo - Gigabyte GA-K8NS-939 (BIOS version F9)
CPU - AMD Athlon 64 3000+ Winchester 1808 MHz - 67 watts
Video Card - Apollo AGP 6600GT GeForce 6600GT 128MB 128-bit GDDR3 AGP 4X/8X
Memory - 1 Rosewill DDR400 (PC3200) 512MB DIMM 2.6V
Memory - 1 Kingston DDR400 (PC3200) 512MB DIMM 2.6V
HD - Western Digital Caviar SE WD800JD 80GB 7200 RPM SATA 3.0Gb/s
HD - Western Digital 20 GB
OS - Windows XP Pro SP 2

Future HW & Sys Specs
Power Supply - Allied AL-A350 ATX 350W
MoBo - Gigabyte GA-K8NS-939 (BIOS version F9)
CPU - AMD Athlon 64 X2 4200+ Toledo 2.2GHz - 89 watts
Video Card - Apollo AGP 6600GT GeForce 6600GT 128MB 128-bit GDDR3 AGP 4X/8X
Memory - 1, Rosewill SDRAM DDR400 (PC 3200) 512MB DIMM 2.6V
Memory - 1, Kingston SDRAM DDR400 (PC 3200) 512MB DIMM 2.6V
Memory - 2, A-DATA SDRAM DDR400 (PC 3200) 512MB DIMM
HD - Western Digital Caviar SE WD800JD 80GB 7200 RPM SATA 3.0Gb/s
HD - Western Digital 20 GB
OS - Windows XP Pro SP 2

Do you think I should get a bigger power supply?

Thanks in advance,
Charles

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This thread highlights the common question of whether a stronger PSU is needed when upgrading CPU and adding memory. Several members rightly pointed out that component ratings and connector compatibility matter (, ), and that graphics hardware is often the dominant load (, ). The most reliable way to decide is to measure actual system draw and allow reasonable headroom rather than picking a number at random.

Practical steps: measure whole-system AC draw with a plug-in watt meter while idle and under realistic load (run a CPU+GPU workload briefly). Convert measured AC watts to required DC output by dividing by the PSU efficiency (for example, divide by 0.80 for an 80% efficient unit). If a meter is not available, a reputable online calculator can estimate peak draw. When stress-testing, keep runs short and watch temperatures; avoid prolonged torture on an older PSU.

Selection guidance: choose a quality unit from a known vendor with an 80 PLUS efficiency level, adequate combined +12V amperage for CPU+GPU, and modern protections (OVP/OCP/OPP/SCP). Prioritize stable rail amperage and correct connectors (main ATX, CPU/EPS, any GPU power plugs) and prefer a PSU with ~20-30% headroom above measured peak to stay in the efficient part of the curve and allow future upgrades. Cheap, unlabeled PSUs often fail to deliver rated wattage, and age decreases reliable output—replace units that are many years old.

Troubleshooting notes: random reboots, failure to POST, or voltage drift are classic signs of insufficient or failing PSU. A multimeter or PSU tester can verify rail voltages under load. Efficiency, not total rated wattage, drives electricity cost—a higher-rated efficient PSU does not necessarily increase the power bill. Further reading and an estimator tool: and background on efficiency standards: 80 PLUS.

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All 13 Replies

Member Avatar for bobbyraw

I notice you did not mention anyting about the other devices wattage usage. yes thay all have wattage usage. especially your HDD. your cd burner, your video card....... However the more power you have the better. depending on what you are plannig on doing with the pc. but more power can't hurt. got for the 450watts

Member Avatar for ReverseC

Thanks. Are you aware of any Win or dos utility that displays the amount of watts you are consuming? I've looked for one but was unsuccessful. I suppose this would be hard to total up for each device in an easy to read format.

Thanks,
Charles

Member Avatar for bobbyraw

each device has that printer on it or on the documetation that came with it. try this utility Sandra 2007 it goes indept and give all sorts of info about all your attached devices

Member Avatar for ReverseC

I checked out Sandra 2007. Pretty cool program. You can download the free version. I decided to go ahead and upgrade to a 450W from a 350W. Thanks.

Member Avatar for jbennet

Most modern video cards need 450w+ btw

Member Avatar for Serunson

My computer curently uses a 570W PSU, which is ample for my gfx card, 2gig ram, HDD, DVD/CD drive and the various other things in there.
The more power the better!

Member Avatar for jbennet

The more power the better!

No because more power = more heat

Member Avatar for Serunson

Not if you have the correct cooling, Most PSU's today come with either 1 Very large fan attached, or 2 smaller ones. My Trust 570W PSU has two 10cm Diameter fans attached. Ample Cooling. But yes more watt's = more heat disipated.

Member Avatar for ReverseC

More power = more $$ to pay when the power bill comes. I try not to over allocate.

Member Avatar for az49er

Did your new MB need the 24 pin attachment? Most new boards need the 24 pins and one 12 vt for the MB and a 12V for video card. If your missing any of these inputs, you may need to upgrade the power supply to get the inputs you need. 500 w is very common, for about 75$. worth the investment.

Member Avatar for ReverseC

My MB requires a 20pin w/ a 12 vt. I went ahead and bought a 450 watt PS. Works great so far. My new Athlon 64 x2 2.2 GHz CPU has been using ~90 watts.

This is what I got:

Rosewill Stallion Series Dual Ball Bearing Fan RD450-2-DB ATX V2.2 450W Power Supply 115V/230V CSA, UL, TUV, FCC

Member Avatar for hardy540

i think you should go with a 400w or a 450. your HDD and you disk drive use up a lot of power also

Member Avatar for Serunson

450W should be ample for most tasks, but if you have more PCI expansion cards than usuall, (e.g. a sound card, 2 gfx cards, ethernet card, usb expansion card etc.) then you may want to look for something with over 500W.

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