Yup, i noticed that sometimes it actually goes up to 10 or 20 or something silly, and that screenshot was only for that specific time i guess.. :/ I dont have a lot of experience with iStats but it was the only tool i had to instantaneously check the current status of the GPU, but it probably wasn't that good like you said.
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I tried! Lol well i have a little update:
So, I got a hold of two cards, Gigabyte r9 390x 8GB for $247 and and a Diamond R9 Nano 4GB for $220 at Microcenter.
The Nano has a single 8 pin while the 390x uses a 8+6 pin combo.
R9 NANO
First I tried powering the nano directly with a 6pin to 8pin cable, but it’s a no go because the power cuts and the system shuts of. Unplugging the cMP IEC (power cable) for a few seconds and plugging it back it allowed to do a system reset so I can try again. If I didn’t do this, the computer would not power up no matter the amount of button presses I do. Now for the next test, I switched to a dual 6pin to 8 pin and it works fine, computer booted up and went to the login screen, however, this is when I noticed the artifacts. The screen looked like it was refreshing and each time I moved the mouse or dragged windows around, I can see it stutter and leave “ghost images.”
To fix the issue, I went on and edited the info.plist for Baffin at /System/Library/Extensions/AMDRadeonX4100.kext and added the identifier 0x73001002 and rebooted the system. Worked like a charm, with everything including Metal supported.
Now time for the tests, I used luxmark, geekbench, and bruce-x 5k. No other programs or windows are running during each of the tests. For Bruce-X, I deleted the event from the library and created a new one each time I test it, and background render is disabled.
The results are as follows:
Luxmark: 11662
Geekbench: 77179
Bruce-X 5K: 25 seconds average over 5 tests
Not too bad, close to what im getting with my single rx 480 setup. I just actually ran luxmark on single 480 card and came out to be 11483 so very comparable. However, the Nano was a little bit faster on bruce x by itself vs. the 480.
R9 390X
Now on to the R9 390X. I took out the Nano and replace it with the card. Tired powering it with a 6pin and a 6-to-8pin plug directly from the mini ports from the cMP and it boots. No need to edit any kext at all, and I’m wondering if its making use of the previous kext edits I did (including the one for the 480) and I can do normal low gpu tasks like watching youtube and browsing forums etc. But as soon as I fire up fcpx to try and render or try luxmark or geekbench, the display shuts off but the mac pro itself does not power off.
Switched over the power setup to utilize the 2 mini 6pin as one 8pin, and one 2xSata from the drive bays to 1x6pin. Booted the cMP and resumed the tests. This setup worked. Like the Nano, I fired up luxmark, geekbench, and bruce-x on fcpx. Now there is one thing that messed up here, I was able to do geekbench and brucex with no issues, but when I try luxmark, the system shuts off. So either my dual sata ports aren’t supporting the 6 pin or the 2x6pin-to-8pin wasn’t… either way I wasn’t gonna let it keep running that way, so I externally powered it with another psu. Now everything else works, and I continued with the tests.
The results are as follows:
Luxmark: 16494
Geekbench: 127195
Bruce-X 5K: 19 seconds average over 5 test
Holy balls its as fast as my dual rx480 setup! Its faster on single luxmark and definitely blazing fast for the geekbench score. The brucex result was pretty much the same with my dual rx 480s, so im wondering now if I have the 2nd card then I’ll probably get a bit more performance.
Fun time?
So for shitz and giggles I mounted both the Nano and 390x to ports 1 and 2 and powered them using the external PSU I already had out and ran the benchmarks ive been doing. The geekbench scores were the same, individual luxmark gpu scores were the same, and the combined luxmark obviously changed. Here are the results:
Luxmark combined: 28250
Bruce-X 5K: 22 seconds average over 5 tests
Now for the brucex, sometimes it would run at 19 and sometimes up to 24seconds so to me, it seems as if fcpx is using whatever is faster and not utilizing both cards together, or whatever is on slot 1. Who knows? I had a hunch that fcpx doesnt work with different cards but I figured, hey why not try it myself while im at it?
Now what do I get from all of this? Personal satisfaction and reason to move on with my life,… somehow. I’ll be returning the R9 Nano as I think that it requires more power by itself and I don’t get any significant performance boost out of it from my dual rx 480. I also checked the power draw from the two cards during stress test at luxmark, and on Idle i was getting about 150 and hitting 480 at full blast, a delta of about 330W for both cards total.
So now, Im looking to find another r9 390x and will be powering it externally. Now my question to you guys is, should I get the same exact gigabyte version or can I get by with say an MSI version? Reason I ask is that I haven’t been able to find any two similar cards up for sale anywhere for a reasonable price. The other Gigabyte R9 390x that microcenter stocks is located an hour and a half from me, so with tolls and gas and my precious time, at $247+ tax it might cost me about $300. Amazon and other online/retail stores current have them for atleast $380 which doesn’t tickle my fancy. I like my discounted cards.
So can I mix and match brands?
