Question Radeon VII's two 8pin power connectors

Mar 29, 2019
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So I want to order a Radeon VII but I noticed it has two 8-pin power connectors.

I've had a 290x for years, and the power consumption seems to be exactly the same as Radeon VII at 295 watts, but the 290x has an 8-pin and a 6-pin, which is all my power supply has.

The 6-pin connectors can plug directly into the 8-pin sockets, and the power consumption is the same, so would I be right to assume I can just plug an 8-pin + a 6-pin into the two 8-pin sockets on the Radeon VII?

Technically two 8-pins are overkill at 375watts, I'd assume is for overclocking??

I've done some searching but haven't come across a definitive answer, and I don't want to rig an adapter somewhere because I would have to hardwire it since all of my plugs are occupied.
 
Mar 29, 2019
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Oh well, I ordered a 6pin to 8pin adapter.

If the two extra pins are only grounds, I'm confused how it's supposed to provide an extra 75 watts. More amperage per 12v wire??
 

DSzymborski

Titan
Moderator
Oh well, I ordered a 6pin to 8pin adapter.

If the two extra pins are only grounds, I'm confused how it's supposed to provide an extra 75 watts. More amperage per 12v wire??
It's not about "can" it's about "should." Theoretically, you could send 360W through three 18 AWG wires. That doesn't necessarily means you should and ATX specs prioritize safety.

I wouldn't use an adapter in your situation, but it is your PC's safety for you to consider or ignore as you deem fit.
 

Karadjgne

Titan
Ambassador
It has to do with the nature of the pinouts.

The sense pins are used by the gpu to determine whether there's a 6pin or 6+2(8pin) connected. Without those sense pins the gpu will not power up.
Has nothing to do with actual power consumption by any particular gpu, it has to do with power availability for every possible gpu.

So a 6pin will have the blue sense A pin, but not the green sense B pin.

Actual power rating is 60w (12v x 5A) per pin, so theoretically the rating on a 6pin at max is 120w, and the rating on a 8pin is 180w max, but industry standards have reduced this to 75w for 6pin and 150w for 8pin. With one sense wire, it tells the gpu there's only a 75w expected draw available, with both sense pins it tells the gpu there's a 150w expected draw available. Per connection. With 2x 8pins, gpu is expecting a possible supply of 300w from the pcie. With a 6pin/8pin the gpu only sees a 225w possible draw, which isn't enough according to the gpu.
 
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Mar 29, 2019
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Well I guess I will keep everyone posted on whether it works or not. I've had this PSU since about 2010, maybe before, across 3 different builds, the most recent being the most power hungry, and it hasn't hiccupped once. It's got an FX-8320 watercooled and overclocked to 4ghz (just a small OC, haven't had time to redo it, was previously 4.6ghz), the 290x, two mechanical drives and two SSD's, and running 6 fans, running basically 24/7 as long as I've had it and it's been a super reliable PSU.

It has two rails at 22 amps and one at 25 amps. I have no idea which rails go where but I would assume the 25 amp rail carries the 8pin PCI-E connector, and the other rails at 22 amps would be 211 watts rms at 80% efficiency per rail. So more assuming but I assume the PSU and the wires would be safe pulling 150 watts from the 6pin connector, or closer to 130 watts according to the Radeon VII power graph, but we'll see.

Do we have any idea which 8-pin plug on the card is PCI-E2?? Just to be safe I'd like the use the adapter on the PCI-E2 slot since it looks to draw less power than PCI-E1.
 
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Radeon VII - $699.
New power supply to protect your investment - $69.
Avoiding the possibility of losing your new Radeon VII due to catastrophic power failure - priceless.


Your 9 year old Antec is out of warranty (it only had a 3 year warranty) and you will be using an adapter that is not covered under warranty.
 
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Mar 29, 2019
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Radeon VII - $699.
New power supply to protect your investment - $69.
Avoiding the possibility of losing your new Radeon VII due to catastrophic power failure - priceless.


Your 9 year old Antec is out of warranty (it only had a 3 year warranty) and you will be using an adapter that is not covered under warranty.
This might sound stupid but I don't trust 99% of what's on the market today. Not even the new version of this same power supply.

And imho it can still have many years left. I have a test bench power supply made from a PSU out of a system that is over 20 years old and albeit doesn't get used 24/7 like my Antec, it still works fine, and has probably seen a lot more abuse. I've ran an entire 12v electrical system of a Cadillac off of it and overloaded it other times and she still fires right up. To sum, I'm not worried about my power supply at all.
 

DSzymborski

Titan
Moderator
I'm not sure what's causing the skepticism - power supplies are far better designed on average than they were 10-20 years ago, more efficient, better voltage regulation, nearly eliminating ripple, etc. Even mediocre PSUs today tend to do these things as well as quality, older group-regulated platforms.

But again, it's your choice. We can't make your decisions for you, but we're all still going to give you the best advice we can.
 
Mar 29, 2019
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I'm not sure what's causing the skepticism - power supplies are far better designed on average than they were 10-20 years ago, more efficient, better voltage regulation, nearly eliminating ripple, etc. Even mediocre PSUs today tend to do these things as well as quality, older group-regulated platforms.

But again, it's your choice. We can't make your decisions for you, but we're all still going to give you the best advice we can.
Not sure, maybe it's the marketing I don't like. They look sort of cheap, too blingy. A lot of the power claims that dont match the rail amperage IE a PSU claiming 1000watts with a 50 amp rail. Typical shenanigans when it comes to power ratings, same as audio amplifiers.

Don't get me wrong I've looked around at new ones, just figured if it ain't broke, don't fix it. As long as it's working and my power demands don't really increase, I should be fine.
 

TJ Hooker

Champion
Ambassador
A lot of the power claims that dont match the rail amperage IE a PSU claiming 1000watts with a 50 amp rail. Typical shenanigans when it comes to power ratings, same as audio amplifiers.
Pretty sure there have always been PSUs that do that, and probably always will be, especially on the cheap end. I mean, if you're talking specifically about amperage on the 12 rail(s) not adding up to the advertised PSU wattage, your current PSU does that too. Modern, quality units actually do a much better job of this.

If you don't want to get a new PSU that's up to you, but trying to justify that choice by implying today's PSUs are generally worse than old ones just doesn't make sense.
 
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just figured if it ain't broke, don't fix it. As long as it's working and my power demands don't really increase, I should be fine.
Power supplies are a bit different and are one thing it doens't hurt and can actually help prevent catastrophe if you replace it when it gets too old. Most good power supplies today have 5-10 and even 12 year warranties. As mentioned earlier your's only had a 3 year warranty. It's mainly about the warranty, because if it blows your system under warranty then the manufacturer covers the cost. If it's out of warranty then you lose your system.
 
Mar 29, 2019
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Well it's been in for about a week and it seems to be doing fine. I've had a couple of bsod's but I'm pretty sure it's unrelated to the adapter. Only on a couple certain games which I haven't tried again, was just testing. It bsod once on Fallout 4 and once on Insurgency Sandstorm and I would chalk it up to drivers as both games are poorly optimized. Both happened in the first 5 minutes of gameplay. Had about a 4-5 hour problem free session on RE2. Other than that it's a quick card and runs a lot cooler than everyone says. Highest temp I saw was 64c. Otherwise it runs mostly in the 50's. Anyways just keeping you all updated. See ya.

Oh and also checked out power supplies again. I think I'll stick with the one I have now. The reviews out there for new ones are scary. Way too many failures for me to feel comfortable with a new one.
 
Well it's been in for about a week and it seems to be doing fine. I've had a couple of bsod's but I'm pretty sure it's unrelated to the adapter. Only on a couple certain games which I haven't tried again, was just testing. It bsod once on Fallout 4 and once on Insurgency Sandstorm and I would chalk it up to drivers as both games are poorly optimized. Both happened in the first 5 minutes of gameplay. Had about a 4-5 hour problem free session on RE2. Other than that it's a quick card and runs a lot cooler than everyone says. Highest temp I saw was 64c. Otherwise it runs mostly in the 50's. Anyways just keeping you all updated. See ya.

Adapters seem to work fine from the start. It's weeks or months later they can melt. You very well could be fine, but I personally would not chance it with such an expensive GPU.

Oh and also checked out power supplies again. I think I'll stick with the one I have now. The reviews out there for new ones are scary. Way too many failures for me to feel comfortable with a new one.
What PSUs and reviews are you looking at?
 
Once again, if you buy a new good quality PSU and it ends up being crap, it is a fluke and the manufacturer will replace it and any parts it damages. If you keep your PSU and it fails, which is likely since you will be using one of the most power hungry GPU on the market today, you lose everything.

Whatever is keeping you from buying a new power supply is simply illogical and isn't considering all factors of the equation.
 
Mar 29, 2019
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The PSU I have now is literally the best rated power supply on newegg. Review after review of people saying it's lasted them 5,7, 10, years and still works. It's discontinued now and Antec's quality seems to have gone down hill since then.

I looked at some newer Antecs and after seeing a lot of failures in the reviews I sorted them by best rated from all brands. There were a couple that might be alright, an EVGA and another one I can't remember, seem to be rated almost as good as my Antec but I'm dealing with a death in the family and his estate so I have some extra costs to deal with for the time being.

It seems to be working fine so I'll keep an eye on the connectors and wires but there's not much else I can do. I ran the 290x for 5 years and it pulls the same power, just a bit more from the PCI slot than the Radeon VII, and a bit less from the PCI-E connectors, so overall power draw from the PSU hasn't changed, just where the power comes from is a little different, and each rail has more than enough power to feed the card, so I'm not worried unless I run into problems.
 
You are still ignoring the fact it is out of warranty and your GPU will have cost $700.

Power supply is not the part to skimp out on.

I'll give you some options.

Power Supply: Corsair - CX (2017) 750 W 80+ Bronze Certified ATX Power Supply ($69.99 @ Amazon)
Power Supply: SeaSonic - FOCUS Gold 750 W 80+ Gold Certified Semi-Modular ATX Power Supply ($92.77 @ Amazon)
Power Supply: Corsair - TXM Gold 850 W 80+ Gold Certified Semi-Modular ATX Power Supply ($99.99 @ Amazon)
Power Supply: EVGA - SuperNOVA G3 750 W 80+ Gold Certified Fully-Modular ATX Power Supply ($99.99 @ Amazon)
Power Supply: SeaSonic - FOCUS Plus Gold 750 W 80+ Gold Certified Fully-Modular ATX Power Supply ($109.99 @ SuperBiiz)
Power Supply: Corsair - RMx (2018) 750 W 80+ Gold Certified Fully-Modular ATX Power Supply ($109.99 @ Amazon)
Power Supply: SeaSonic - FOCUS Plus Platinum 750 W 80+ Platinum Certified Fully-Modular ATX Power Supply ($119.99 @ Amazon)
Power Supply: EVGA - SuperNOVA G2 750 W 80+ Gold Certified Fully-Modular ATX Power Supply ($129.99 @ Amazon)
 
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TJ Hooker

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The PSU I have now is literally the best rated power supply on newegg.
Even if that was a good metric of quality (it isn't really), it took me all of about 10 seconds to find one with equally high (slightly better actually) ratings. https://www.newegg.com/Product/Product.aspx?Item=9SIA85V4R42309
Here's another one with even better ratings: https://www.newegg.com/Product/Product.aspx?Item=N82E16817151187

Like I said, if you don't want to get a new one that's fine. Just don't pretend it's because your PSU is better than anything on the market today.
 
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Jul 26, 2019
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You are still ignoring the fact it is out of warranty and your GPU will have cost $700.

Power supply is not the part to skimp out on.

I'll give you some options.

Power Supply: Corsair - CX (2017) 750 W 80+ Bronze Certified ATX Power Supply ($69.99 @ Amazon)
Power Supply: SeaSonic - FOCUS Gold 750 W 80+ Gold Certified Semi-Modular ATX Power Supply ($92.77 @ Amazon)
Power Supply: Corsair - TXM Gold 850 W 80+ Gold Certified Semi-Modular ATX Power Supply ($99.99 @ Amazon)
Power Supply: EVGA - SuperNOVA G3 750 W 80+ Gold Certified Fully-Modular ATX Power Supply ($99.99 @ Amazon)
Power Supply: SeaSonic - FOCUS Plus Gold 750 W 80+ Gold Certified Fully-Modular ATX Power Supply ($109.99 @ SuperBiiz)
Power Supply: Corsair - RMx (2018) 750 W 80+ Gold Certified Fully-Modular ATX Power Supply ($109.99 @ Amazon)
Power Supply: SeaSonic - FOCUS Plus Platinum 750 W 80+ Platinum Certified Fully-Modular ATX Power Supply ($119.99 @ Amazon)
Power Supply: EVGA - SuperNOVA G2 750 W 80+ Gold Certified Fully-Modular ATX Power Supply ($129.99 @ Amazon)
I would go with seasonic they are making great psu's right now my fav =)
 

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