TDP vs Total power consumption?

[gran172]

Hey, i have a I5-4590, on intels website it says "TDP:84w" i've read some information regarding cpu power consumption and i know that tdp does not equal total power consumption, but is it at least close to it's maximum power consumption? There was an article on toms that showed the I5 going as high as 120w while gaming, could it 40w off it's maximum consumption? Is there anyway to know it's maximum power consumption? Most sites show it's tdp only

 

[Ecky]

A laymen's explanation:

TDP - thermal design point. Intel tends to rate a line of CPUs all the same, so all of their CPUs that fit into a socket can use the same motherboards, heatsinks, and be cooled in the same environment. There's no way the i7 4790 draws the same power as the 4690, because it's higher clocked, has HT, and more cache, but they can both run safely with the same heatsink in the same case.

If these chips exceed an average of 84w usage over a period of time (defined by bios generally) they'll throttle back until they're below that average, but on desktop CPUs the TDP is higher enough than their typical power draw that they never throttle.

Just as an example, my i5 3570K only draws about 45w under full load (as measured at the wall by a Kill-A-Watt), despite its 77w TDP.

 

[gran172]

So was the article i read that the I5 4590 was using around 120w way off? Is around 84w a good estimate of how much power my cpu uses?

 

[13thmonkey]

why are you asking? What question are you trying to answer. It's important because it will change the answer that you are given.

 

[gran172]

I'm trying to know how close to the edge i'm with my psu (430w), with a R9 380-I5 4590. I'm guessing around 340-370w? I'm aware that quality is far more importante than the total wattage of the psu, but it would also help so i can know which psu i should upgrade to next whenever i can afford it

 

[13thmonkey]

very close to the edge. Precisely which PSU is it?

 

[GhislainG]

So was the article i read that the I5 4590 was using around 120w way off? Is around 84w a good estimate of how much power my cpu uses?

Intel XTU displays the TDP; stress test the CPU and you'll see how much power it draws. Mine has a TDP of 90W while running Prime95 28.5 Small FFTs, but nothing else can make it that busy. With the more realistic version 26.6, the TDP only is 59W.

 

[Ecky]

I own a kill-a-watt, which is a wonderful multipurpose tool. My entire i5 3570K (77w) + HD7850 (130w) PC, under Prime95 + Furmark, only draws about 180w at the wall, which translates to a little more than 160w on the 12v side of the PSU (90% efficiency).

TDP doesn't necessarily reflect what it's actually drawing, but good practice if you're not overclocking is to add up the TDPs of the major components in your system, then give yourself an extra 33% headroom (minimum).

In your case, you're looking at 84w + 190w = 274w, plus maybe another 25-50w for other components such as RAM, fans, motherboard. A 430w PSU should be plenty so long as you're not overclocking either heavily. You can probably get away with a mild to moderate overclock that doesn't increase voltage.

 

[Ecky]

Here's a graph of how many watts my i5 draws (at the wall) at various frequencies, with the lowest stable voltage:

I've isolated CPU power draw, by subtracting total system load wattage from system idle wattage. It's not perfect, but it's a good approximation.

Notice how it rises quickly after ~3200mhz, and goes exponential after ~4000mhz.

 

[13thmonkey]

I own a kill-a-watt, which is a wonderful multipurpose tool. My entire i5 3570K (77w) + HD7850 (130w) PC, under Prime95 + Furmark, only draws about 180w at the wall, which translates to a little more than 160w on the 12v side of the PSU (90% efficiency).

TDP doesn't necessarily reflect what it's actually drawing, but good practice if you're not overclocking is to add up the TDPs of the major components in your system, then give yourself an extra 33% headroom (minimum).

In your case, you're looking at 84w + 190w = 274w, plus maybe another 25-50w for other components such as RAM, fans, motherboard. A 430w PSU should be plenty so long as you're not overclocking either heavily. You can probably get away with a mild to moderate overclock that doesn't increase voltage.

Correction, A good 430W,,,

 

[gran172]

I own a kill-a-watt, which is a wonderful multipurpose tool. My entire i5 3570K (77w) + HD7850 (130w) PC, under Prime95 + Furmark, only draws about 180w at the wall, which translates to a little more than 160w on the 12v side of the PSU (90% efficiency).

TDP doesn't necessarily reflect what it's actually drawing, but good practice if you're not overclocking is to add up the TDPs of the major components in your system, then give yourself an extra 33% headroom (minimum).

In your case, you're looking at 84w + 190w = 274w, plus maybe another 25-50w for other components such as RAM, fans, motherboard. A 430w PSU should be plenty so long as you're not overclocking either heavily. You can probably get away with a mild to moderate overclock that doesn't increase voltage.

Wait, why 84+190w? I thought the 380 used around 290w?

 

[gran172]

Intel XTU Benchmark says that when my cpu goes up to 3,4ghz it uses around 105w. So 290+105w? Or is it not realistic to be stressing the cpu that much on a regular gaming situation?

 

[GhislainG]

It depends on the game, but most if not all keep the CPU way below 100% utilization.

Edit: My i5-4590 reaches 3.66 GHz and the maximum TDP is 73W on the benchmark.

 

[gran172]

So my cpu shouldn't go above 84w? In the benchmark i got around 105w for "Turbo boost short power max", what's that supossed to be then?

 

[13thmonkey]

precisely what psu do you have, your power draw is close enough that it is really important.

 

[gran172]

http://www.evga.com/Products/Product.aspx?pn=100-W1-0430-KR
I've already made lots of threads regarding my PSU and i'm aware that i'm kind of on the edge, what i want to know is realistically how many watts my system is actually using

 

[GhislainG]

So my cpu shouldn't go above 84w? In the benchmark i got around 105w for "Turbo boost short power max", what's that supossed to be then?

When you hover CPU Total TDP you see 105W?

 

[gran172]

I do know that my I5 will use around 84w, what i do not know is my GPU, i've read lots of forums, some say it uses 190w, some say it uses around 300w, that's a huge difference, are there are trustworthy site for this?

 

[gran172]

So my cpu shouldn't go above 84w? In the benchmark i got around 105w for "Turbo boost short power max", what's that supossed to be then?

When you hover CPU Total TDP you see 105W?

Here's a picture: http://imgur.com/OLCqsTp

 

[GhislainG]

Why are you so worried about the PSU? The total power draw while gaming probably won't exceed 300W and the PSU provides 408W on the 12V rail.

 

[13thmonkey]

with that psu i'd be happy.

with an average psu i wouldn't.

 

[gran172]

Well, when i bought my pc the vendor said that 430w would be enough since i didn't know anything about them, would be nice to know if he ripped me off haha, plus lots of people have already told me i should change my psu as soon as i can because it's just not enough. I actually gave him a call a few days ago and he said that it's enough and that i have some room for some overclocking as long as i don't change the voltage, when i asked this on the forums it was a big no, i'm not sure what to believe right now?

 

[13thmonkey]

Why are you so worried about the PSU? The total power draw while gaming probably won't exceed 300W and the PSU provides 408W on the 12V rail.

Precisely why I asked the question a dozen posts ago.

 

[13thmonkey]

You've got enough to cope with your system as is, do not OC. do not upgrade the GPU (unless it decreases electrical power like a 970 might).

 

[gran172]

You've got enough to cope with your system as is, do not OC. do not upgrade the GPU (unless it decreases electrical power like a 970 might).

Well that's a relief. Thanks a lot everyone