2nd 7850 won't work

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giddonah

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Nov 2, 2013
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MOBO: Gigabyte 970A-D3 (updated bios via windows utility) - I had this already, I'm wondering if this isn't a weak spot in the build

CPU: AMD FX-8350 (cooled with a Corsair H80 liquid cooler) - Would like to OC it eventually

RAM: 2x4Gb DDR3-1866

GPU: 2xSapphire HD7850

HDD: Samsung 256GB SSD

PSU: Seasonic SSR-650 - wondering if this isn't powerful enough? I also had this already

So I ran passmark and was getting unimpressive results. Both GPUs showed in CPU-Z, but I noticed the fans on the 2nd card weren't spinning during the benchmark. I pulled power from the 2nd card and re-ran the benchmark and it was almost the same. I checked the Catalyst Control, and crossfire was enabled.

Is the MOBO junk for this application (gaming)? Not enough watts? I'm open to replacing either or both.
 
I was thinking that, but googling the psu issue comes up with a lot of people saying that psu is fine for two 7850's. When I plug my stuff into that calculator I get a minimum of 350w, recommended 400w, which is 100w lower than newegg's calculator. I'm having a hard time accepting that a relatively new seasonic 650, which is made for crossfire, is incapable of supporting this.

I did some tests with Passmark 8.0:

With one card (second card removed power plug and crossfire connection):
Overall: 3095
CPU: 9433
2D: 591
3D: 3836
RAM: 1382
Disk: 1991

With two cards (made sure crossfire was enabled in Catalyst Control):
Overall: 3079
CPU: 8923
2D: 579
3D: 3997
RAM: 1279
Disk: 2360

My old system (i5 3550 I think, and like a 460GTX):
Overall: 3339
CPU: 7132
2D: 805
3D: 2996
RAM: 2389
Disk: 1567


At this point, I'm thinking the motherboard is holding everything back. But if the PSU really can't handle this, I don't mind upgrading, since I'll pretty much have a whole other computer from parts at that point.
 
In the pass I had to reset my cmos to pick the other card up for crossfire.. worth a try at this point but you will need to reset up the bios once it boots.
 
But if the fans are not running, something else is wrong. Do you know of have an extra psu or know of anyone that has one you could borrow? BTW Amazon has a fantastic return policy. If you don't mind paying for shipping.
 
That's one of the really odd things. Sometimes the fans do run. I checked during that last passmark test, both cards' fans were spinning.

On another note, the CMOS bricked the computer until I can get a PS2 keyboard. Yay. At least I still have my old comp, which at this point is on par with my new one... :/

My old comp also has a seasonic 650, it's an upgraded version, but it's a few years old now. I could try swapping them, but that one doesn't have a 8-pin cpu plug, just a 4-pin, so I don't know what that'll mean for the CPU. Although... I could hack the hell out of it by powering one GPU with one PSU, and the other GPU with the other PSU. A little awkward, especially considering I'm 2 min away from giving up and just buying a new motherboard. Hell, look at the damn hit in RAM performance I took. I also don't think the thing is capable of 8x/8x even if it did work. I think it's 12x/4x. Big deal?
 
Thanks. Kind of a setback, but I definitely learned something today :)

I'll update when I get things running again.
 
I'm not sure how well Crossfire will run on that board, the second PCIe is x4. 970 chipset mobos weren't really designed for Crossfire/SLI.
 
Yeah. I'm discovering that point. I'm currently shopping for a new mobo because not only will it solve the crossfire problem, but I took a huge hit in RAM performance on the switch too. I'm hoping the whole thing will change when I do this right.

I was crossing my fingers, and I lost.
 
Just bought a ASUS M5A99X EVO R2.0. I had similar problems - bad mobo. Hard to detect. Pretty good board it supports SLI and Crossfire. It's a tight fit and it doesn't like my Sound Blaster Z card. Amazon has it for $115 after rebate. So far ( after a day) it's a good board
 
I gotta say that should be enough power, it's not that close to be worried about unless things are acting funny with the new mobo. I just can't see getting a better mobo as a loss, either. I guess if you don't enjoy taking everything apart and putting it back together again with new mobo smell permeating the room, it is, but man I'd be like "Yippee". Any excuse I get to go parts shopping I'll take it.
 
Oh yeah, I'm definitely not taking this problem as a downer. I bought the same mobo as dude4life. I am now just a PSU away from a complete separate computer, which I might have anyway. I'll be up and running by tuesday/wednesday. Looking pretty good, considering I wasn't really planning on a new comp right now.
 
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