I get it it's miss leading
no it doesn't stand for total power draw
and many manufacturers insist on reading it differently
lets discuss thermal design power and clear up the misinformation
lets consider an i7 7700K
intel rates its TDP at 91 watts what this means is that a cooler you place atop this CPU
would have to dissipate 91 watts of power output in the form of heat transfer
in order to keep this CPU running as it should
the cooler above is much smaller than required and thus has a much lower thermal design
it may only dissipate half the heat given off by the CPU for example
resulting in sky rocketing core and package temperatures thermal throttling
and possible system failure
another thing to note a processing unit's TDP will also change if its frequency and voltage change
we discussed this in our crash course playlist
every computer enthusiast knows that overclocking a CPU or GPU always "always" results in a higher thermal outoput
and here's the catch voltage doesn't have to change
on paper this really doesn't make sense if voltage ultimately drives resistance we're talking Ohm's Law here
and resistance is converted to heat than a voltage change of 0 should yield a thermal design change of 0
but thanks to how transistors work clock speed directly affects TDP
here we go
as transistors switch from an active state to a passive state and back again to an active one
they release heat thanks to partial resistance remember
so as clock speed increases so to does the alternation rate
it isn't directly proportional a frequency at 4 gigahertz doesn't mean that your transistors are alternating at 4 billion times a second
it actually means they're alternating at higher rates than that and if you overclock all cores in your chip equally
which you have no choice but to do when it comes to GPU's most of them have several thousand cores
thermal output increases at a rather obtuse exponential rate
this means that for every factor 1 of overclock lets says 100 megahertz
heat is generated at a factor grater than 1
this value varies from chip to chip but explains why past a certain frequency
chips become very stubborn and get very "very" hot regardless of voltage input
your essentially asking transistors within your processor to alternate at rates
much higher than they were thermally designed for so if you wish to venture any higher that threshold
typically around 5 gigahertz or so special cooling systems are required
and remember this is all thanks to the second law of thermodynamics no system is perfect
every thing loses energy in the form of heat your own body does
our Sun does the Earth does in-fact the entropy of the entire universe is increasing
and from the vastness of galaxies down to the very transistors powering your computers and phones
you're using to watch this video at this very moment
every thing is currently giving off heat
be sure to check out that full video why do processors get so hot via the link bellow
so when frequency increases partial resistance increases resulting in a higher operating temperature
same goes for voltage and you can figure that one out with Ohm's Law
and as a general rule of thumb overclocking a processor often requires a beefy air cooler or AIO
all this to say TDP is usually an underestimate of total power draw under load
even a 7700K at stock frequencies will draw more power under full load than its TDP
Steve from Gamers Nexus helped me to clear this one up
you see TDP isn't a set in stone measurement standard it should be easier to see with intel CPU's by this point but
the trend carries over to other component's from other companies in dicey ways
consider this PNY GTX 1080 Ti its an insane graphics card one of the most powerful
single GPU card's you can currently buy running on the founders edition reference pcb
and its "Graphics Card Power" quote enquote is vaguely inferred by NVidias website at 250 watts
I'm nit picking here because "Graphics Card Power" isn't necessarily TDP
and on top of that NVidia's not specifying whether this is "GPU Power" alone or GPU+VRM+VRam power
total board power
it gets confusing
now with this card power draw can reach upwards of 300 watts which still isn't bad mind you considering how
powerful this card is
but I should note that this is not a consistent trend it is very infrequent
I don't have the equipment for individual component power testing its actually more difficult than it sounds
but other websites I trust including Tom'sHARDWARE
do this on a daily basis
so you can see here absolute peak power draw occurring for a fraction of a second 295 watts
that's well over 250 watts of TDP that the card is rated for
and if you had chosen a power supply based on summed up component TDP's
and decided to play any sort of intensive game you might find yourself tripping your power supply
and crashing your system or thermal throttling
I'm not saying its guaranteed but you'd be awfully close to doing that
but for a vast majority of their testing the Ti when tortured averaged at around its TDP
through these examples you can clearly see why you cannot simply extract TDP and derive power draw directly
it depends on the unit as well as the manufacturer
and what general practices were being followed at the time
by this point if you're quite confused don't worry i was in the exact same boat I had many questions to ask
the tech community in glad that Steve and Others were able to help me out so thank you for that
but if there's one thing that you can and should take away from this video
it is clarified perfectly
by VSG from Thermal Bench He says that no matter what your power input
will always be higher that your heat output
and if you think about it it has to be if power consumption matched heat output
than the unit would literally just be a space heater and do no electrical work
so I'm closing here's a summed up simplified explanation of the difference between TDP and power draw
the unit in question draws "X" amount of power in watts
from the wall and dumps "Y" amount of heat in watts
shortly their after
where "Y must be less than X"
now when it come to deciding how much power your pc will draw under load
it can help to starting with TDP's and then multiplying by some sort of safety factor I tipically use 1.5 just
to be on the safe side for example if my CPU's TDP is 100 and my graphics card is rated at 300
i multiply 400 watts by 1.5 and end up with
around a 600 watts PSU to be comfortable
if I plan on doing some serious overclocking ill adjust the multiplier accordingly
if how ever I'm supporting several fans a large pump many hard drives led strips et cetera
then might want to tack on an extra 100 watts just to be on the safe side these components can actually drain quite a bit of power from your power supply
while the safe power zone is usually subjective under no circumstance would you want to run this kind of PC
its a beautiful pc by the way
with a 500 watt power supply that would just be insane
you'd most certainly be outside your curves peak efficiency discussed in more detail right here
and that's assuming you're delivering enough power to your components to keep them running in the first place
if you have any questions or concerns leave those in the comments bellow
check out the links bellow to the products showcased
in this video and also check out Gamers Nexus's Channel for more in depth stuff like this
the guys over there cover quite a bit of material that is honestly beyond me
if you liked this video be sure to give it a thumbs up thumbs down for the opposite click the subscribe button if you haven't already
and I will catch you in the next video this is science studio thanks for learning with us