How much wattage does underclocking a Radeon save? (RX 550/Radeon Pro WX3100 question)

[GunsMadeAmericaFree]

Short Version:
2 questions:

1) What is the typical relationship between underclocking a Radeon and maximum power Wattage draw? For example, if I would underclock it 10%, would that lead to 10% less wattage use?

2) Is there any way to make this simple and repeatable on bootup?


Long Version:

I'm in a situation where I have a SFF Lenovo desktop PC, and would like to upgrade the video from the onboard Intel HD graphics. Since it is a small form factor PC, I am limited to half height/low profile cards.
I presently get a 3Dmark Sky Diver score of 951 on it. For 95% of our casual games, this is fine, but I'd like to be able to do some with 3D.

From what I've read, this PC is limited to 45 Watt video cards, so I initially thought I would be limited to tracking down a 30 Watt GT 1030 card for it, which gives a G3Dmark score of ~ 2,200.

However, then I noticed that the Radeon RX 550 uses up to 50 Watts, and gives a G3Dmark score of 3,400. I found myself wishfully thinking, "Hmm, if only I could get that wattage down by 5 watts or more, I could
use the Radeon in my system. I recently found a used Radeon Pro WX 3100 low profile card for a decent price. Evidently it uses the same core as an RX 550, is within 3% of the same specs, and has the same 50 Watt
power use ceiling. I'm wondering if I might be able to use the gaming drivers that are available for it, underclock it 10% to 15%, and end up with a much more capable card than the GT 1030 I thought I would have to
make do with. Of course, I would need to make certain that it automatically does this on bootup each and every time, and I'm not sure there is an easy way to accomplish this.

If anyone has previously underclocked a Radeon card in order to decrease Wattage draw in a similar manner, I would be interested in hearing your experience. Thanks!

 

[naukkis]

It probably would work fine as it is, but you can simply reduce GPU max power use by decreasing it's power limit in drivers. If 50W card power limit set to -10% max power use will be 45w.

 

[GunsMadeAmericaFree]

It probably would work fine as it is, but you can simply reduce GPU max power use by decreasing it's power limit in drivers. If 50W card power limit set to -10% max power use will be 45w.

Wow, I had no idea that there was something like that you can edit in the driver. Can you point me to a resource so I could read up on that? Is it as easy as bringing up something like a text file and then editing the text? That is amazing, I've never even heard of this before. Then again, I've never been interested in underclocking a video card before, either. Thanks!

 

[naukkis]

Wow, I had no idea that there was something like that you can edit in the driver. Can you point me to a resource so I could read up on that? Is it as easy as bringing up something like a text file and then editing the text? That is amazing, I've never even heard of this before. Then again, I've never been interested in underclocking a video card before, either. Thanks!

It's not that complicated, there's slider in AMD drivers to control power limit.....

https://www.amd.com/en/support/kb/faq/dh-020

There's a lot of stuff for optimizing best performance, but changing power limit isn't complicated at all.

 

[Stuka87]

Really no point in manually underclocking. You can either set down the power limit so the card does this on its own (as mentioned above), or you can undervolt and get lower power consumption without hampering performance (and in some cases increasing it).

 

[GunsMadeAmericaFree]

Trouble in paradise, guys. I purchased the RX 550 low profile card and tested it today. It seemed to work fine, but the whole system rebooted when I was running 3Dmark and stressing the card. It was probably because it was drawing 50 Watts - a few more than the 45 watt limit the Lenovo SFF PC says I can draw with a video card.

Evidently I NEED to use Wattman to lower the power limit. Trouble is, there is no Wattman to be found - it isn't present at all. When I check in device manager, I find:
Device ID 699F, which is evidently AMD I also find Sybsystem Vendor ID 1002, which I guess is Lexa Pro RX 550/550X

So, it is evidently a card manufactured directly by AMD. I'm guessing that this was some sort of OEM pull. Does this mean I'll never be able to access Wattman in order to lower
the power limit of the card? If that is so, then I'm afraid that this card will never be stable on this SFF system with a small power supply.

Do I have to return it, or is there some way to force it to give me access to Wattman for lowering the power limit 10% to 15%? I think that is the only way it would be stable
for gaming on this system. Thanks for any help.

I have also attached a jpeg with info about my system, and another showing lack of a Wattman choice under Global Settings.

 

[Stuka87]

Interesting. It must be that its an OEM card, as the normal RX550 does have wattman support.

But the fact that is crashes is reason enough to return it. You should never need to mod a card just to get it to run at stock speeds.

 

[naukkis]

Overclocking features could be disabled or enabled in bios. You can read bios from card, edit it to enable OC features, or directly set bios performance and power levels to wanted level.

https://www.techpowerup.com/rbe/

With wrong bios setting it's possible to make card not bootable, usually reflash of working bios is still possible with other gfx card, eg. integrated.

https://github.com/IndeedMiners/PBE-Polaris-Bios-Editor-1.7.2/releases/tag/1.7.2

There seem to be signatures in nowadays secure UEFI's so there's need to disable all security features when using modified firmwares.

 

[GunsMadeAmericaFree]

Interesting. It must be that its an OEM card, as the normal RX550 does have wattman support.

But the fact that is crashes is reason enough to return it. You should never need to mod a card just to get it to run at stock speeds.

To be fair, this thing only has a 240 Watt mini power supply. Since the card draws 50 Watts normally, and the specs said not to try drawing more than 45 Watts, I was
depending on being able to set a lowered power draw to make everything work well. It ran just fine when doing DX11 benchmarking, but when doing the more demanding
DX12 tests, that was when it rebooted. I think it would be fine if I could just set the power draw lower by about 10% or 15%.

Wow, according to GPU-Z, temp shot up to 80 degrees C (~176 F) within 120 seconds of starting to run Unigine Superposition. I'm not sure if I'm impressed with the fan or heatsink on this. I already thought that the fan and heatsink seemed on the very small side before seeing the temps.

 

[Guru]

Try and use different software like MSI Afterburner, they support a bigger range of gpu's.