Another 'Overclocker's dream' - good job AMD.
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AMD RX 480 Fails PCI-E Specification
- Thread starter tripkebab
- Start date
Another 'Overclocker's dream' - good job AMD.
Man of Honour
Reviews show performance reduced by a small amount with the new drivers set to pit the card in spec. That's not "gimped". It's also almost certainly safe to run it with an out of spec draw through the PCI-E 6-pin, so "safe" isn't really the right word either.
I wouldn't buy a reference RX 480, but I wouldn't say they were unsafe or gimped to make them safe.
I might buy a 3rd party RX 480 though, if it had a good cooler and an 8-pin PCI-E connector and it didn't pull more than 75W through the motherboard. 75W through the motherboard and anything up to 150W through an 8-pin PCI-E connector would be absolutely fine and I doubt if an RX 480 would need more than 225W unless perhaps if it was very efficiently cooled, overvolted and overclocked. I'll be looking for reviews of cards like that when they come out.
Man of Honour
Pretty much. The new drivers give you 2 options:
1) Same degree of power throttling with the power draw altered to pull less from the PCI-E motherboard slot (bringing it into spec) and more from the 6-pin PCI-E connector (taking it further over spec). This gives slightly higher performance due to driver optimisations. The over-spec draw on the 6-pin PCI-E connector shouldn't matter as the whole chain from PSU to graphics card is usually rated for way over spec anyway. The wires and connector at the graphics card end would probably handle 100% over spec. The connections on the reference RX 480 itself probably would too. The PSU end is less certain, but I wouldn't care unless I was using a £20 PSU and I wouldn't be using a £20 PSU.
2) More power throttling to bring the overall power draw down to within spec for both power supplies. This gives slightly lower performance.
It's still a disappointing margin though, with almost no scope for overclocking. And it's not a 150W card. Not unless it's power throttled enough to reduce performance noticably or it undervolts well.
Man of Honour
7950 here...with a hefty overclock, +20% power draw...and it's still running much cooler than it did at stock because of the amount of voltage I was able to hack off, while power throttling much less. Even at stock, just reducing the voltage and increasing the allowed power draw greatly increased performance and greatly reduced temps.
The axe analogy is very apt because you don't even have to be precise about it. This isn't a fine scalpel sort of thing, where you take off a millivolt at a time.
And who said this? Amd? No just random leaks online that as usual everyone started to take as fact.
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Soldato
I'd love to know the details of that one as I really need to run one on very low voltage draw if at all possible but I forget which util is best as Ive run it at stock so long
Associate
Deleted : not worth arguing if the video doesn't explain it. Pulling more than 75w from the 6 pin is not an issue as the video clearly explains. It is the slot that is the issue.
Man of Honour
Sure. I'll pit it here as it's still indirectly relevant (undervolting will bring an RX 480 into spec and increase its performance as well).
I stumbled into the issue indirectly a couple of years ago when I installed better hardware monitoring software and was concerned about the VRM temps on my graphics card (97C when overclocked). My goal in undervolting was to reduce temps, not increase performance. I didn't know how much a card could be power throttled even straight out the box.
I used (and still use) MSI Afterburner. It works with any card, not just ones made by MSI. My card is a VTX3D X-Edition. I didn't install the video capture and framerate monitoring parts of MSI Afterburner, but that wouldn't make any difference regarding settings and performance. It works and it's extremely easy to use, so I use it. Set and forget for everything - GPU voltage, VRAM voltage, aux voltage, GPU and VRAM speed, power limit increase or decrease, fan profiles. It also has monitoring and monitoring over time as a line graph (which allows you to roughly measure power throttling).
I did a lot of testing with different settings and benchmarks, but this was 2 years ago and I've forgotten the results. I did make a post with 4 typical results for stock and a sort of start, middle and end of tuning:
https://forums.overclockers.co.uk/showpost.php?p=26333269&postcount=5
Key bit:
That's a hell of a performance increase solely from reducing power throttling. In addition, I got huge drops on GPU temp and graphics card VRM temps. Golden. The benchmark with those results was Unigine Heaven 4.0 at 1920x1080 ultra quality custom preset with 2xAA and no tesselation.
I did a bit more tuning afterwards and I'm now running at these settings:
GPU voltage: 1.019V
GPU clock: 1 GHz
VRAM voltage: 1.500V
VRAM clock: 1.4GHz
That gets me 58.3 fps on the same benchmark as above with good temps. I might be able to get a bit more out of it, but I got bored with tuning and left it at that.
MSI Afterburner at default will allow you to undervolt a 7950 GPU down to 800mV, which is almost certainly much more than low enough. 1.5V is the minimum on the VRAM, +/- 20% is the limit on the change in power limit. You can extend the ranges of variation by editing a specific Afterburner text file to add a specific bit of text stating that you understand that you're doing it entirely at your own risk without any support (a deliberate restriction by the author). Instructions are here:
http://forums.guru3d.com/showthread.php?t=338906