Reusing old 420W power supply - Comments please.

[buildingacomputer]

I understand large power supply is needed to run video cards. Since I will use onboard video, I don't need to buy 600W or larger power supply, right?

Phenom II X4: 125W (no overclocking)
AMD 790GX onboard graphics: 30W
Mobo: 30W
HD : 20W
DVD : 20W
Wireless PIC card: 5W
CPU cooler fan: 5W

Total 235W

Comments please.

 

[PottedMeat]

You'll hit ~235W peak at 100% CPU and video usage only. You'll be fine.

 

[HOOfan 1]

Of course the wattage the manufacturer rates it at might not be truthful. It depends on the quality of the PSU.

 

[mm2587]

I ran a PII x4 125W with a 785g board, 3 hard drives, dvd drive, wireless card and a creative audigy card with the 5.25 breakout box on a 300 watt psu with no problems.

 

[modestninja]

When you say old 420W power supply, how old are you talking?

If it's old enough, it might not have the right connections you need the 420W may be on the wrong rails.

Another consideration is as power supplies get old, the amount of load they can handle decreases, so even if it was a good 420W to start with, it may not put out that much power any more. It's pretty hard to comment or answer your question when you don't give us any information about this 420W PSU.

 

[doubleOseven]

What's the make/model of your 420 W power supply? You have to look at the amps listed on the power supply label for each voltage. Old power supplies (i.e. 8+ years ago) were designed to put out more amps on the 5 volt line as computers back then had CPUs that tended to feed off the 5 volt line (requiring more amps). Computers of today require power supplies that have more amps on the 12 volt line. As an example, and old 420 watt power supply may have: 5V=30 amps, 12v=13 amps. A new power supply may be 5v=20 amps, 12V=35 amps.

 

[jpeake]

I just built a Core i5-750 rig, with an ATI 5870 and two SATA hard drives, and reused my "old" Thermaltake 430W PSU.

Stable at 3.8Ghz @ 1.3vcore.

 

[VirtualLarry]

I just built a Core i5-750 rig, with an ATI 5870 and two SATA hard drives, and reused my "old" Thermaltake 430W PSU.

Stable at 3.8Ghz @ 1.3vcore.

How did you connect the ThermalTake 430W? The TR2-430 units that I am familar with, only have a single 6-pin PCI-E connector. Doesn't the 5870 take two?

 

[buildingacomputer]

My "old power supply" is Thermaltake 420W. I bought it for my Athlon X2 (939 socket?) machine about 4 years ago. I will check 5V and 12V ratings tonight. Thanks for the tip.