AMD Radeon HD 7790 vs AMD Radeon R9 390X

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NascarBoy119

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Hey all,

I'm planning on building building a new PC soon. I've already got everything else on my parts list ready, aside from the GPU. I was planning on going with an R9 390X for my build, as it seemed to be the best card for my price range. However, I was recently looking on eBay and it seems that HD 7990s are going for around $250, and that seems like a steal to me. Now, I know what you are thinking in your heads: "They will set ur house on fire and use as much powr as a Nuclear plant!1! also, crossfireX doesnt work properly.,.,. ".

For one thing, I could care less about power consumption. As long as it doesn't consume 3000 watts or something, it'd be fine. As for the temperature, I don't think that would be a big concern. According to most sites, it reaches about 80°C under load, which isn't TOO bad. It probably would be cooler for me, as I keep my house set to about 21°C, and I also plan on having maximum air cooling in my case. I've heard that there were some problems with CrossfireX scaling, however I believe that is 99% fixed in the latest drivers. I know the R9 390X will be faster and more efficient then the HD 7990, but is it worth the extra $180-$200? They both support DirectX12 and can max all games at 1440p. Suggestions would be great.
 
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Rogue Leader

Rogue Leader

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Its more about the features. For me if I was doing it all over the R9 390x has freesync. I'd get a Freesync monitor too and enjoy screen tear free gaming. The 390X also has more memory (which does nothing for you now but maybe in a couple years...). Thats where you get the benefit here.
 
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NascarBoy119

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I'm looking to make a build for around $1000-$1100 not including the monitors. I want to have a 5760x1080p setup with triple monitors. I can find a bundle with 3 1080p monitors for about $300, so $1400 for everything total. I'm thinking $400-$440 max for the GPU, though cheaper is always better xD. That's why the HD 7990 looked so attractive to me. In the future, I'd perhaps crossfireX it with a 280X (as HD 7990 crossfire seems a bit problematic).

Here is what I plan on getting for the rest of the build:
CPU: i7-4790K
RAM: 16GB DDR3 @1600Mhz
Mobo: Asus Z87-Pro (or Z87-Plus)
Case: Corsair Spec-02

EDIT: I just looked at the comparison you posted, but you forgot to looks at the R9 290X in 'Uber' mode. While in that mode, it seems to beat the HD 7990 in Civilization: Beyond Earth and Shadow of Mordor, but I don't play any of those games so it isn't a big deal. In everything else, the HD 7990 seems to equal or beat the 290X 'Uber'.
 
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jimmysmitty

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Do you mean the HD7970? The HD7970 is weaker than the R9 390X and you wouldn't be able to crossfire it with a R9 280X even though they are the same GPU it wont work thanks to some internal changed AMD made.

If you are planning to game at that resolution then you are better off with a R( 390X for the extra VRAM.

http://pcpartpicker.com/part/asus-video-card-strixr9390xdc3oc8gd5gaming

They are all pretty close in price.
 
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NascarBoy119

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No, that was a typo on my part. I meant the HD 7990, which I believe is 2 HD 7970 Ghz Editions Crossfired.
 
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jimmysmitty

jimmysmitty

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Yes a HD7990 is two 7970s but not GHz, they are clocked at the original HD7970s specs.

That said, a R9 390X would be the best option for the resolution you are planning to game at because of the extra memory. For 1080P/1440P you normally want 4GB of VRAM and the HD7990 has 6GB but that is 3GB per GPU so it is still like having a 3GB GPU.
 
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NascarBoy119

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Hmm, I thought I heard somewhere that the 6GB of VRAM was shared by the two cards, thus having an effective 6GB of VRAM. If it is 3GB per GPU, then perhaps the R9 390X will be my best bet for triple-monitor gaming? It just seems that the R9 390X is a bit overpriced, as you could get 2 HD 7990s for $500...
 
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jimmysmitty

jimmysmitty

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The HD7990 is a dual GPU card. It is the same as having two HD7970s in Crossfire.

The way crossfire works is that the memory is effectively 6GB however each GPU has access to 3GB of VRAM. Even though the point of Crossfire/SLI is to split the load between the two GPUs they both still render the same information.

So if a game needs 2GB of VRAM then each GPU will need to use 2GB of VRAM meaning the game will be able to use 3GB total before slow downs come into play.

A single HD7990 will be faster than a R9 390X but the extra VRAM of the R9 390X will make it better for playing at higher than 1080P resolutions since the higher the resolution the more VRAM you tend to need.
 
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