Power Supply Unit recommendation

Jameslim1008 · Sep 14, 2014

Hello, I'm buying new computer parts but cannot seem to choose which power supplies to get, I tried every single psu calculator online but they give me varying results. It would be great what u guys think is recommended power wattage for my spec.
Asus z97 d3h(?)
Intel i7-4790k (planning to OC to 4.4GHz probs around 1.35 volts)
Gigabyte GTX760 2GB OC (planning overclock)
Corsair H80i liquid cooler
1 LED corsair fan
1 corsair fan (Standard)
Samsung evo840 250gb
WD black faex 1tb 7200rpm
2x4GB hyperX predator 2166mhz
DVD-RW optical drive
And possibly 4 additional USB devices

Thanks!

Wolfshadw · Sep 14, 2014

If I were building that system, this is the power supply I'd probably go with: Seasonic S12II 620 watt

-Wolf sends

ko888 · Sep 14, 2014

For a system using a single NVIDIA Reference Design GeForce GTX 760 graphics card NVIDIA specifies a minimum of a 500 Watt or greater system power supply that has a maximum combined +12 Volt continuous current rating of 30 Amps or greater and that has at least two 75 Watt 6-pin PCI Express supplementary power connectors. Some of the non-Reference Design GeForce GTX 760 cards have a single 150 Watt 8-pin (e.g. ASUS GTX 760 DirectCU II OC) or two 150 Watt 8-pin (e.g. MSI GTX 760 HAWK) or one 75 Watt 6-pin and one 150 Watt 8-pin (e.g. Gigabyte GTX 760 WindForce OC, EVGA GTX 760 SC w/ACX Cooler, MSI GTX 760 TwinFrozr Gaming) PCI Express supplementary power connectors.

Total Power Supply Wattage is NOT the crucial factor in power supply selection!!! Sufficient Total Combined Continuous Power/Current Available on the +12V Rail(s) is the most critical factor.

Overclocking of the CPU and/or GPU(s) may require an additional increase to the maximum combined +12 Volt continuous current ratings, recommended above, to meet the increase in power required for the overclock. The additional amount required will depend on the magnitude of the overclock being attempted.

Make sure that the power supply unit you get is confirmed to be Intel Haswell compatible when tested according to Intel's testing procedure.

The Seasonic S12II 620 Watt PSU is not Haswell compatible.

Wolfshadw · Sep 14, 2014

@ko888 - That's some good info that I was not aware of.

-Wolf sends

dottorrent · Sep 14, 2014

XFX XTR 650w - http://www.newegg.com/Product/Product.aspx?Item=N82E16817207031&cm_re=xfx_xtr-_-17-207-031-_-Product

Wolfshadw · Sep 14, 2014

Re: Haswell Power Supply Compatibility

I found this article on The Tech Report: The big Haswell PSU compatibility list. In it, it states:

Before we proceed, we should be clear about one thing: you don't, strictly speaking, need one of these "Haswell-ready" PSUs to build a Haswell system. Corsair told us that it "fully expects" motherboard makers to let users disable the new low-power power state in the firmware. Cooler Master went even further, stating that, to its knowledge, "all mainboard vendors" will disable the new low-power state in their boards by default. In other words, you may never encounter any issues even if you pair a Haswell platform with an incompatible power supply.

-Wolf sends

ko888 · Sep 14, 2014

Wolfshadw :

Cooler Master is clueless. I have just built a system, a few days ago, with a Z97 chipset motherboard and a Haswell refresh i7-4790K CPU and the in the GIGABYTE motherboard's UEFI BIOS setup the C6/C7 power states were set to [Enabled] by default. I built a Haswell based system for a friend last year. Guess what? The ASUS motherboard's BIOS setup had the C6/C7 power state support enabled by default.

Just because you can disable the C6/C7 power states in BIOS does not make a PSU Intel Haswell compatible.

Here's what jonnyGURU.com says:

So I've seen a lot of companies posting that their group regulated PSUs are
"Haswell ready". Sure.. anything is Haswell ready if you disable C7 sleep state
in the BIOS, but that doesn't meet Intel's definition of Haswell ready, so it's
sort of misleading.

If any of you reviewers with load testers want to duplicate Intel's testing for
Haswell:

Put 0.1A on +12V1.
Put 0.05A on +12V2.
If the PSU has a single +12V rail, 0.15A load on the +12V does the same thing.
Put the maximum load on the +3.3V and +5V.
The way I calculate this is to take the maximum and divide by 4.15 and then
divide by 2.
For example: Max combined for +3.3V and +5V is 150W. (150/4.15)/2=18A per rail.

A pass is when all voltages are within 5%. Typically, the PSU, if group
regulated, will go beyond 12.6V.

I've found that even if the load on the non-primary rails is a more realistic
lower load, like 5A per rail, the PSU's voltages will be in spec, but if the
load suddenly changes, like a drop in the +3.3V and +5V or a sudden rise in the
+12V, the PSU may shut off. This emulates going into or coming out of sleep
state.

Wolfshadw · Sep 14, 2014

So to break it down, Intel doesn't say it's "Haswell Ready" if you have to disable to C7 sleep state.
If you get a power supply that is not "Haswell Ready" by Intel's definition, but you do disable the C7 sleep state, you're not going to run into problems.

Would you agree with those two statements?

-Wolf sends

ko888 · Sep 14, 2014

Wolfshadw :

It all depends upon who is saying that you won't run into problems. Generally it is the older group regulated design PSUs that may run into the problem. Group regulated design PSUs are also not as stable as the modern DC-DC design. You would actually need to test your specific system configuration to determine whether or not it will have a problem. This is only relevant if you already have a PSU from a previous build that you want to reuse in a new build.

The problem is easily avoidable even before you've purchased the PSU, just by selecting an appropriate model. You should never run into the problem no matter what the C6/C7 power state support is set to in the motherboard's BIOS.

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