Do I have enough power supply?

[TheVorlon_44]

Hello friends!

I have a mini-itx system I would like to add a graphics card to.

This is what I have:

CPU
Intel Core i7 4790K @
RAM
16.0GB Dual-Channel DDR3 @ 1200 mhz
Motherboard
ASRock Z97E-ITX/ac (CPUSocket)
Graphics
DELL U3415W (3440x1440@60Hz)
Intel HD Graphics 4600 (ASRock)
Storage
465GB Samsung SSD 850 EVO 500G SCSI Disk Device (SSD)

I am considering a GTX 980 ti as my monitor is somewhere between QHD and UHD (its a "wide" QHD at 3440 x 1440

My current power supply is a Seasonic SS-520FL2 which is "only" 520 watts.

I used a "kill 'o watt" power meter and even with the CPU absolutely maxed out on Prime95 the unit never even gets to even 200 watts total draw, and even under pretty heavy usage it barely gets over 120 watts most of the time.

The TDP of the GTX 980 ti is listed at 250 watts so this would seem to suggest at most I "might" see 400 watts even under really extreme situations, and that 250 to 300 watts would seem to be a "normal" heavy usage scenario.

My understanding is that ideally power supplies should be run at about 50% as this is the sweet spot from an efficiency point of view.

So why does NVidia and all the sites recommend at least 600 watts for a power supply?

The SS-520FL2 is a fanless unit, and my understanding is that is is basically just a 700-800 watt unit that has been "derated" to be fanless.

I think a SS-520FL2 is more than ok in my situation... am I missing something?

Thanks!

 

[turkey3_scratch]

A GTX 980Ti can draw 300W on a torture test, overclocked a bit more.. Ignore wattage calculators always. 4790K overclocked under torture, I'd say looking at 150W perhaps a bit more. Rest of system added in, probably looking at 515W under peak torture conditions for the machine with an OC 4790K and 980Ti. I would look into a quality 550W or 650W PSU. Realistically, under gaming conditions, your build will probably draw 400W. Another important factor is that rated wattage in power supplies must be ignored. Every power supply has the theoretical ability to deliver infinite watts, or amps. A 300W power supply if it is required to deliver 1000W, technically can do so, but due to its components being rated for lesser degrees of electrical current, they will burn up if the PSUs protections don't shut it down first.

I'd look for a quality 650W unit for your purposes, though a quality 550W will do. EVGA G2 650W is great, Seasonic as always is great.

 

[TheVorlon_44]

A GTX 980Ti can draw 300W on a torture test, overclocked a bit more.. Ignore wattage calculators always. 4790K overclocked under torture, I'd say looking at 150W perhaps a bit more. Rest of system added in, probably looking at 515W under peak torture conditions for the machine with an OC 4790K and 980Ti. I would look into a quality 550W or 650W PSU. Realistically, under gaming conditions, your build will probably draw 400W. Another important factor is that rated wattage in power supplies must be ignored. Every power supply has the theoretical ability to deliver infinite watts, or amps. A 300W power supply if it is required to deliver 1000W, technically can do so, but due to its components being rated for lesser degrees of electrical current, they will burn up if the PSUs protections don't shut it down first.

I'd look for a quality 650W unit for your purposes, though a quality 550W will do. EVGA G2 650W is great, Seasonic as always is great.

Have you had your hands on a Seasonic SS-660XP2...?

It's semi passive and what I can tell its verry similar to the SS-520FL2 I have, except it has a fan that kicks in at high wattage.

 

[turkey3_scratch]

Not me personally but they are very high quality.

 

[Vic 40]

I would just keep what you have.With a max turbo of 4,4ghz is there not alot of reason to overclock that cpu and if you choose a 980 ti that only has need for 1x6pin+1x8pin pcie power connector do i not think it will go over the TDP that nvidia gives for this.
If this is for gaming will it not push that system to max TDP so would you imo be fine.

 

[TheVorlon_44]

I actually have my chip set to turbo one core to 4900, 2 cores to 4800, 3 cores to 4700, and 4 cores to 4600.

The motherboard is set of offset the cpu voltage and goes to 1.298 volts, but defaults back to .697 volts when idle.

Borrowed a friends 980ti and maximum measured power with a "kill o watt" was about 380 watts.

 

[Vic 40]

That 380watt is what's drawn from the wall,not even what the pc actually uses.You can probably,looking at the psu you have,take 10% off.