[SOLVED] Is my 650W Power Supply adequate for 1920X + RX 480 Crossfire

[Deankavanagh1999]

Hello there guys, I was just wondering if my 650w psu is enough for my PC, which consists of:

- Threadripper 1920X
- RX 480 Crossfire
- 16GB hyper x 3200mhz RAM
- Nochtua u14s TR cooler
- 1 TB HD
I wonder this as I have been having poor performance with the two cards when crossfire is enabled, such as stuttering, large fps drops and the fans hardly spin as much as they should (single card they ramp up fine) which leads me to believe that they are not being utilised well enough, maybe due to a lack of power being delivered to them?

One thing to note is that I was not having these issues before I upgraded to the TR platform! Before I had an i7 6800k and that is all I have changed. I did find a guy on YouTube who claimed that he was having issues with a RX 480 CF setup, with an AMD FX CPU (cant remember the specific one) and a 650w psu! He claims that he was getting stuttering issues as well as shut downs. Although I have not experienced any shutdowns, my experience does sound similar to his and he said that upgrading to a 1000w psu completely fixed all issues.

Therefore, do you guys think I could be having a similar issue and that 650w is not enough for my system?

 

[feelinfroggy777]

I would go with a bigger PSU for a 1920x and two 480's. And not all PSUs are created equal. A cheap 650watt PSU wont get that much wattage on the 12 volt rail and that is where you need it. I would get a quality 850 watt PSU from EVGA, Corsair, or Seasonic.

 

[Deankavanagh1999]

Hey there, I should have mentioned that my psu is a quality one, an EVGA GQ.

 

[feelinfroggy777]

Hey there, I should have mentioned that my psu is a quality one, an EVGA GQ.

Yeah, the GQ is a decent PSU. But 650 watts is not a lot for a Threadripper CPU and 2 Rx 480 GPUs. Especially if you are overclocking.

 

[Deankavanagh1999]

Yeah, its makes sense. You might be thinking why on earth did I think it would be enough? The reason i thought it would be enough is because according to TDP, the combined TDP of the CPU and the two GPU's is only around 480w! Maybe I severely underestimated the power pull of this system?

 

[madmatt30]

What are your main uses for the crossfire cards?

The simple fact is crossfire support is dire in a lot of newer titles, low usage is simply down to the load being spread across 2 cards but only using 40-50% of the capabilities of each in these cases.

Simply put though, no 650w simply isn't enough to leave any headroom.

480s are 200w cards, irregardless of amd's initial official spec sheets.

 

[feelinfroggy777]

Yeah, its makes sense. You might be thinking why on earth did I think it would be enough? The reason i thought it would be enough is because according to TDP, the combined TDP of the CPU and the two GPU's is only around 480w! Maybe I severely underestimated the power pull of this system?

Well, TDP does not actually mean how much power the parts use, but it does translate. TDP is actually the amount of heat that a system will need to dissipate. With that being said, for Intel and AMD, their "TDP " also works for power consumption. But that consumption is an average at stock settings.

When the CPU or GPU boost, or when you overclock the power goes way up. Overclocked on Prime95 the 1920x can use more than 300 watts of power by itself. Then, those power ratings are also averages. Both the GPU and the CPU will have moments of power spikes. The power usage is not static. It consistently fluctuates.

If you really want to know what your system is pulling from the wall, then you will need a power meter.

https://www.amazon.com/P3-International-P4460-Electricity-Monitor/dp/B00009MDBU?th=1

 

[Deankavanagh1999]

I get that Crossfire can be hit or miss, however, my point is that with my 6800k before (remember this is all I have changed) I was getting much better scaling! GTA 5 was getting anywhere from 60-70% scaling with relatively consistent frame times. Now I am getting less of boost, maybe 40 ish% and the fps fluctuations are crazy with severe stutter. Yes I know that Crossfire is rarely as smooth as a single card, but , I am now getting worse performance with a platform that if anything, should give me a superior experience to the 6800k with its 64 pcie lanes (giving me 16x for both gpu's) and the 1920x does not game any worse than the 6800k?

 

[Deankavanagh1999]

I see, I forgot to mention is at the stock 3.5 GHZ on all 12 cores. Therefore my question now is, do you think that a 1920x pulls more power than its 180w TDP?

 

[feelinfroggy777]

I get that Crossfire can be hit or miss, however, my point is that with my 6800k before (remember this is all I have changed) I was getting much better scaling! GTA 5 was getting anywhere from 60-70% scaling with relatively consistent frame times. Now I am getting less of boost, maybe 40 ish% and the fps fluctuations are crazy with severe stutter. Yes I know that Crossfire is rarely as smooth as a single card, but , I am now getting worse performance with a platform that if anything, should give me a superior experience to the 6800k with its 64 pcie lanes (giving me 16x for both gpu's) and the 1920x does not game any worse than the 6800k?

The additional lanes on the 1920x have nothing to do with it. The 6800k is a better CPU for gaming though. You dont need 12 cores for gaming. You would do better with fewer and faster threads.

Are you running 2 sticks of RAM or 4? Quad channel memory does not matter for gaming, but Ryzen scales well with faster RAM and Threadripper needs faster RAM even more to communicate across the CCUs. Running only two sticks may really hold the 1920x back, but I dont know for sure as I have only ran 4 sticks in my 1950x.

But if you couple the faster threads of the 6800k with some potential memory restrictions in your current build, then it may equate to the 20-30% scaling loss in games.

 

[Deankavanagh1999]

What memory restrictions would I have? I am using the same 16GB 3200mhz ram that I was using in my x99 setup. Furthermore, the 6800k (especially since I was running at stock) can't be 30% faster than a 1920x!

 

[madmatt30]

I'd put the 6800k & 1920x at pretty much identical on single core peefoemance

 

[Deankavanagh1999]

Thats what I was thinking madmatt. Not that I am trying to disregard you feelinfroggy, but, the 1920x is relatively similar to a 1700x (since the monstrous amount of threads does not get utilised) and a 6800k is not significantly faster than that.

 

[feelinfroggy777]

What memory restrictions would I have? I am using the same 16GB 3200mhz ram that I was using in my x99 setup. Furthermore, the 6800k (especially since I was running at stock) can't be 30% faster than a 1920x!

The 1920x is different form the 6800k. The 1920x is really 2 (8) core chips (2 cores disabled on each chip) that are connected through infinity fabric. The infinity fabric is important because it needs fast RAM. If you are only running 2 sticks of RAM, then those sticks may only be talking directly to one of the CCUs then it will have to send the information to the other CCU. Whereas if you have quad channel memory running, the other CCU will have access to memory that wont need to be sent across the dies. I dont know for sure, as this is not something I have really looked into, but this is a big issue for the 32 core 2990wx because it has 4 CCUs and only quad channel memory. So two of the CCUs do not have the same access as the others, which slows it down.

The 6800k has the memory controller on the same die and does not have these same type of issues because it is a different architecture. As far as the 6800k vs 1920x for gaming performance, I really dont know because I dont have a 1920x or a 6800k. But Intel CPUs have an edge over AMD in gaming performance so I would lean on the Intel CPU to be a better gamer. Look at the gaming performance difference in the 6700 to the 1700x and you will probably see a similar difference between the 6800k and the 1920x.