Is 300 watts enough for a 250 watt build?

[orca-4444]

I'm planning on assembling a gaming PC with an asus M11 computer with an i3-4150. If I add a GTX 950, the build should take up <250 watts of power. Is the included 300 watt power supply good enough to not see a performance drop?

 

[xBlaz3kx]

More is better, always. And choose a quality psu, 80Silver at least

 

[Barty1884]

More is better, always. And choose a quality psu, 80Silver at least

I agree with most of that. More is better, and a quality unit. 80Bronze is just fine - as long as it's a quality unit.
Read here: http://www.tomshardware.com/forum/id-2547993/psu-tier-list.html Tier 1 or 2, 3 if you really must.

Tier 1 units are not generally "budget friendly".

Tier 2:
XFX 550W Bronze @ $56
EVGA SuperNova 750W semi-modular @ $57

Tier 3 units:
Antec VP-450 @ $33
EVGA 430W @ $35 / $25

 

[Dark Lord of Tech]

Extra high quality power 😀

PCPartPicker part list / Price breakdown by merchant

Power Supply: EVGA SuperNOVA GS 550W 80+ Gold Certified Fully-Modular ATX Power Supply ($69.99 @ NCIX US)
Total: $69.99
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-12-23 17:46 EST-0500

or

Enough great power.
PCPartPicker part list / Price breakdown by merchant

Power Supply: SeaSonic S12II 430W 80+ Bronze Certified ATX Power Supply ($53.99 @ SuperBiiz)
Total: $53.99
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-12-23 17:50 EST-0500

 

[BadActor]

Nvidia recommends at least 350 watts. A really good 300 watt would more than likely be OK, but generally the PSU's that come with cases are very poor quality with a few exceptions. See Tom's PSU tiers chart for recommendations on picking a quality PSU:

http://www.tomshardware.com/forum/id-2547993/psu-tier-list.html

The one listed below is a Tier 2 and one I would recommend for your application:

http://www.superbiiz.com/detail.php?name=PS-EA380D&c=CJ

 

[renzhe]

Yes. Your power supply is most efficient around 50% of its capacity, so you want your system there most of the time while not exceeding 100%, which is right where you are. However, if you want more power-hungry components later, you'll want a power supply with more capacity.

 

[sancho_mic]

How did you calculate the 250w of the build?

Assuming it's correct the calculation, the 300w will be just enough for 250w build, but the psu will always work within the upper range of operability capacity and will allow less room for eventual upgrades (additional HDDs, cards, etc.)
It also means that you might have shorter lifespan of the psu, although i believe it has negligible impact...
Performance of the build will not be affected; however the stability depends on the quality of the PSU.