What PSU should I get?

[Doctor Gallop]

Hi, I want to upgrade my power supply to a 650W or even a 750W but with so many options out there how can I be sure which to buy that will be compatible and fit my systems's spec's? It's a full size case measuring 16" high by 16" long by 7 1/2 " wide.
This is my system info:........
System Manufacturer Dell Inc.
System Model OptiPlex 780
System Type x64-based PC
Processor Intel(R) Core(TM)2 Quad CPU Q9505 @ 2.83GHz, 2826 Mhz, 4 Core(s), 4 Logical Processor(s)
BIOS Version/Date Dell Inc. A15, 8/6/2013
SMBIOS Version 2.5
Windows Directory C:\Windows
System Directory C:\Windows\system32
Boot Device \Device\HarddiskVolume1
Locale United States
Hardware Abstraction Layer Version = "6.1.7601.17514"
User Name Owner-PC\Owner
Time Zone Pacific Daylight Time
Installed Physical Memory (RAM) 8.00 GB
Total Physical Memory 7.90 GB
Available Physical Memory 5.56 GB
Total Virtual Memory 15.8 GB
Available Virtual Memory 12.7 GB
Page File Space 7.90 GB
Page File C:\pagefile.sys

 

[Rage_3K_Moiz]

A full-tower Optiplex 780 will accept any standard ATX power supply. I find Corsair to be a pretty good choice for power supplies.

Out of curiosity: Why do you want to upgrade the power supply? Does the current one seem to be failing?

 

[Doctor Gallop]

A full-tower Optiplex 780 will accept any standard ATX power supply. I find Corsair to be a pretty good choice for power supplies.

Out of curiosity: Why do you want to upgrade the power supply? Does the current one seem to be failing?

I have never had a decent computer. I just bought this one after having a very slow running eMachine with a 200W PSU. I am not a "gamer" but there are as few games I would like to play now that I have a better machine. I just ordered a GTX 750ti video card and would now like to upgrade the PSU as well.

 

[EndlessWaves]

would now like to upgrade the PSU as well.

Why? Fitting a higher capacity PSU does nothing for the computer's functionality except potentially drawing a bit more power (PSUs are less efficient at lower loads). The only reason to go for a massive 650-750W PSU is if you're fitting multiple graphics cards and on a seven year old computer like that they'd just be limited by the CPU (not to mention that it may not even have the slots to put them in).

A 750ti draws 60-75W and will happily run in most systems with a 200-300W PSU.

 

[Doctor Gallop]

Why? Fitting a higher capacity PSU does nothing for the computer's functionality except potentially drawing a bit more power (PSUs are less efficient at lower loads). The only reason to go for a massive 650-750W PSU is if you're fitting multiple graphics cards and on a seven year old computer like that they'd just be limited by the CPU (not to mention that it may not even have the slots to put them in).

A 750ti draws 60-75W and will happily run in most systems with a 200-300W PSU.

That's great news. I admittedly know very little about this stuff. But I remember reading in an advertisment for the GTX 750ti that the "required psu for this graphic's card was 400W or better". That was the whole reason I wanted to upgrade the power supply. I figured it was the thing to do. But if you are certain, than there is no need for me to shell out the extra money I don't really have to spend. Thank you.
Note: I bought this machine "refurbished and upgraded". That is why I included the "system info" when I first posted. So does that make a difference in what I need? Thanks for your patience and help.

 

[EndlessWaves]

But I remember reading in an advertisment for the GTX 750ti that the "required psu for this graphic's card was 400W or better". That was the whole reason I wanted to upgrade the power supply. I figured it was the thing to do.

PSUs power the whole system, so any minimum capacity recommendation for a graphics card is based on some estimate of what components it's likely to be paired with. Because there's such a range of systems these tend to be on the pessimistic side, hence the 400W recommendation for a card that only draws 75W itself.

But if you are certain, than there is no need for me to shell out the extra money I don't really have to spend. Thank you.

You haven't told us what power supply the system has now and what other components it's got in so I can't say for sure. 650W is an awful lot though, so even if your current PSU isn't sufficient you don't need to go that high. Big full ATX PSUs don't tend to come in normal capacities any more as most mainstream prebuilt systems have moved to smaller physical sizes so even the smallest 400-500W capacities available in ATX are a lot of power.

 

[Doctor Gallop]

I am going to open it up and read what it says on the psu. I was told when I bought it that it was 330W. Actually, someone gave me an extra GT220 [?] card which I installed and all the games played well, but the card was so loud and noisey I had to take it out. I will get back to you as soon as I take a look inside the machine. It should say right on the psu, right?