will an apu use less power if descreet graphics are used?

[Joshontech]

Lets say I hook a 7750 to and a4 apu I know the 7750 witll over power the gpu on the apu. I was just wondering if the apu shuts off the gpu potion of the chip and in turn conserves power?

 

[JOOK-D]

I guess it depends whether you crossfire the graphics portion of the apu with the gpu itself, combining them. If not, then yes it will be disabled and conserve power. However that won't 'save' you any power since the GPU consumes a lot of power too.

 

[Ra_V_en]

Obviously it does, why do you think Intel and AMD invented those Idle states, CoolNQuite.. etc.
As JOOK-D sait, I'd depends is it actually used or not.

 

[Joshontech]

im not talking about cool and quiet I know all that stuff. Also no i am not cross firing anything because that gpu wont crossfire with that apu.

The tdp of the a4-4000 is 65 watts I wanna know if I install the 7750 if the actual a4 gpu portion of the chip is disabled or will it still consume the same amount of power for no reason?

The reason why I am asking is because I have a 300 watt psu and at the current state of things I will be useing with everyhting maxed out 250 watts which is under the 300 watt limit but really close. I was just wondering if the a4 will use less power there for making the actual total wattage at load lower than 250 watts?

 

[CTurbo]

No. The A4 will still consume ~65w at full load, and I'm sure it will be running at full load all the time. What kind of psu do you have? Is it oem?

 

[Ra_V_en]

No. The A4 will still consume ~65w at full load, and I'm sure it will be running at full load all the time. What kind of psu do you have? Is it oem?

So you are implying i3/i5/i7 uses full TDP while not using its Intel Integrated graphic? You must be joking.
You can do this test on any laptop with integrated gpu, turn on some monitoring software like AIDA and look at current power consumption of CPU. Aida has option to test all cores.

I've done this observations so many times I'm 100% sure it works that way.
On my old laptop with i5-460M when stressing CPU only I hit ~25W max, in the meantime GPU is clocked t 50Mhz. When i put some load on GPU it rises to ~35W. TDP of that CPU is 35W:
Link

So they don't put TDP of CPU only but the whole package which is obvious because you need to get a cooler to meet that requirements.

Back to the topic, it's impossible to absolutely turn off the GPU, even if you have a discrete card the package is too complicated to do so, but instead the GPU module will go down to some kind of idle state where some minor power is used. I couldn't find exact specification but it wont be more then 1-2W or so.

AMD cant use different solution because its a standard for today, if it was it wouldn't be targeted to the same segment.

Edit: Thats why I've said about idle states and CNQ, except of CPU lowering down voltage, frequency, GPU's also do so - 2D/3D mode for example. It's not literally turning off the whole GPU transistors because its not that simple, but most of them which are power hungry.
It's like with a TV in standby mode, it's not using full power, but some electronics needs power supply to respond for wake up call.

Edit2: CTurbo as for a guy who is flashing with CPU badge you are talking a bs in this matter and I'm quite surprised you actually came to such conclusion.

 

[Joshontech]

No. The A4 will still consume ~65w at full load, and I'm sure it will be running at full load all the time. What kind of psu do you have? Is it oem?

So you are implying i3/i5/i7 uses full TDP while not using its Intel Integrated graphic? You must be joking.
You can do this test on any laptop with integrated gpu, turn on some monitoring software like AIDA and look at current power consumption of CPU. Aida has option to test all cores.

I've done this observations so many times I'm 100% sure it works that way.
On my old laptop with i5-460M when stressing CPU only I hit ~25W max, in the meantime GPU is clocked t 50Mhz. When i put some load on GPU it rises to ~35W. TDP of that CPU is 35W:
Link

So they don't put TDP of CPU only but the whole package which is obvious because you need to get a cooler to meet that requirements.

Back to the topic, it's impossible to absolutely turn off the GPU, even if you have a discrete card the package is too complicated to do so, but instead the GPU module will go down to some kind of idle state where some minor power is used. I couldn't find exact specification but it wont be more then 1-2W or so.

AMD cant use different solution because its a standard for today, if it was it wouldn't be targeted to the same segment.

Edit: Thats why I've said about idle states and CNQ, except of CPU lowering down voltage, frequency, GPU's also do so - 2D/3D mode for example. It's not literally turning off the whole GPU transistors because its not that simple, but most of them which are power hungry.
It's like with a TV in standby mode, it's not using full power, but some electronics needs power supply to respond for wake up call.

Edit2: CTurbo as for a guy who is flashing with CPU badge you are talking a bs in this matter and I'm quite surprised you actually came to such conclusion.

Well thank you ra_v_em that was very detailed and well thought out. I actually didn't mean that the gpu would shut off entirely I meant what you said a extremely low power state.

I also understand that 90% of the time a pc component never reaches its full TDP unless you are trying to stress test it and even then most of the time it does not reach it fully.

I got the 7750 today and installed it. Two things I would like to note that I found out. One is that I actually have a 350 watt PSU wich makes things a little better and two the 7750 that I got would only fit in my PCI-e 4X slot due to wi-fi and sound card.

 

[CTurbo]

You can't compare mobile cpus to desktop cpus. Everything about mobile cpus are designed for the lowest power draw possible to protect battery life.
Desktop cpus don't need to be quite so efficient, and efficient is one of the last words I would use to describe AMD. Let's take the A4-5300 for example. It's slightly older and slightly faster than the A4-4000. It's rated at 65w just like the A4-4000. You want to know how much power you could save by disabling it's igpu? Well guess what. AMD makes that for you, and it's called the Athlon x2 340. It is the EXACT same chip as the A4-5300 except it's down clocked 200mhz and has it's igpu physically disabled. AMD rates it at 65w also. Real world tests will show you that the power saved over the A4 apu is insignificant. 10-15% at best. That's 6-9w at most. And that is with a chip that has no trace of an igpu. You think one with an igpu not in use is going to be the same? The power saved would be even more insignificant. Now I know that a 65w cpu doesn't just hum along at 65w all the time, and I also know that it has to be seriously stressed to stay around it's max tdp, but everybody knows AMDs are power hogs and you can't assume that it's going to stay around ~35w all the time because your igpu is not in use. A 350w psu doesn't put out 350w all the time either. 350w is the max output it's capable of. Crappy psus have trouble hitting their max wattage. All psus work best when they can operate no more than 75-80% of their max wattage rating. It's not good to keep your psu stretched to it's limits all the time.

Intel cpus are much more efficient. Here's a good example of igpu vs no igpu. The i7 3770 and the Xeon e3-1230v2 started out as the exact same chip. Cut from the same exact sheet. One goes on to become the 3770 and one goes on to become the 1230v2. The only difference is the Xeon is factory downclocked 100/200mhz and has it's igpu physically disabled. Intel rates the i7's tdp at 77w, and the xeon's at 69w. That is a power savings of 11%.
For what it's worth, the newer 4770 is 84w and the newer 1230v3 is 80w. Even less of a difference.

Simply put, disabling integrated graphics is NOT an acceptable way of saving power.

 

[Ra_V_en]

CTurbo i cant get a clue what you mean.
When you say that TDP is a value that will be used 100% of the time the PC is running then its obvious this statement is wrong.
If it was this way then there would be no point of making temp reading from IDLE to LOAD, because it would be the same.
Laptop was only an example because I actually did some tests due to overheating problems and wanted to find out how to handle it well.
Obviously there is a gap on design in Laptop/PC CPU/GPU especially in power consumption, but the rules are exactly the same.
If some part of the unit is not used, for example 3 cores of CPU, its power consumption is going down. Its the same with GPU... why the hell on bitcoin mining you can actually see how high your temps and power consumption will go, because it uses almost 100% of the gpu.

"Simply put, disabling integrated graphics is NOT an acceptable way of saving power"....
I'd say its actually opposite, even its 10W cut its still saving. Until some proper tests are done we don't know the real numbers but those numbers are real and exist for sure.
Even if the gpu part of the cpu takes max 10W from those 65W of apu, its still 65 - part of those 10W, its simple as that. It wont be 10W because some resources are used for CPU and GPU so you cannot simply switch them off.

All wee need is a guy with APU who will run Aida-like software and compare power drain from 100% CPU and 100%CPU+100% of build in GPU, then we have a real answer.

So Joshontech it is true it will save some portion of the of the TDP but as far as we don't know the real values this portion can smaller or bigger but for sure not NONE.