I have an old power supply with the following characteristics:
PORSCHE Model: P4-450W, 20+4 pin connectors

Recently I am assembling a new PC with the following parts:
GPU: Gigabyte GTX 1080
CPU: Intel Core i5-6500
Motherboard: MSI z170A
RAM: DDR4 2800-16GB

Is my old power supply enough for my new PC or I should buy a new one? What are the possible effects of using the current old power supply?

3 Answers 3


Get yourself a decent power supply from the likes of Seasonic or Corsair. The Corsair RM550x would do just fine.

You have high end components, make sure you have a good power supply. It's important to make sure the PSU supports all the C states from the CPU.

  • Thanks. So, what is the effect of using the old PSU?
    – Hossein
    Apr 25, 2017 at 11:26
  • 1
    @Hossein, maybe it'll work, maybe it won't, maybe it'll catch fire. Your current PSU has only about 70% the 12V output of a 450W PSU from Seasonic or Corsair, and modern computers draw almost all their power from the 12V line. You'll be on the edge of overloading your current PSU, and no-name brands don't have the reliable overload protection that quality brands do.
    – Mark
    Apr 25, 2017 at 20:12
  • 1
    @Hossein like mark said, it's better to use a new PSU with a brand new PC. There is always degradation in hardware. Old PSU's also don't support the newer C states that the CPU is capable off. That could result in a system not wanting to boot and big stability issue's. No-Brand PSU's also don't have the quality CAPS like real brands do. So when using such a high end GPU and decent hardware, get a brandnew one. Apr 26, 2017 at 8:49

Yes it will be enough... I estimate that your rig will consume 350W under load, in which case you would need a PSU that handles 400-450W to allow for a little headroom. So you have that...

However, the PSU won't be as efficient as it could be, and it doesn't allow for any growth. Maximum efficiency is usually under 40-70% (depending on PSU model) so yours would usually be in the 70-100% bracket.

So if you want to make do, your current PSU will suffice. If you want to plan for the future, perhaps invest in a decent 600W+ PSU.

  • Thanks for your answer. To be honest, I didn't get your comment about efficiency.
    – Hossein
    Apr 25, 2017 at 11:33
  • 1
    If a PSU is 80% efficient (which is typical for a decent brand), then to deliver 350W to your components, it has to generate 438W internally. The wasted energy is then given off as heat. And the efficiency of the PSU varies depending on load: if your PSU is running at half load, the efficiency might be 82%, but at full load, the efficiency might drop down to 70%. So your PSU will work with your components, but at best, it will get hot under heavy loads, and if sustained, it may not be able to deliver what is needed and it will certainly shorten it's life. (So get a decent new one....)
    – CJM
    Apr 25, 2017 at 11:48
  • 1
    @Hossein, power supply efficiency varies with the load. Most power supplies are most efficient when the load is somewhere between 50% and 70% of rated capacity.
    – Mark
    Apr 27, 2017 at 20:14

It cold support it but i would recommend to give your PC headroom and getting something like 550W or 650w, most of those power supplies cost around 90-120 dollars.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.