2x XFX R7990 Rig instant power off (1500W PowerSupply)

[Xeon]

Hi BitcoinTalkers,

I got a issue with my 2x XFX R7990 rig with a 1500w powersupply it go instant off after starting cgminer.
Mining rigs specs:
AMD processor
Motherboard: GIGABYTE GA-990FXA-UD5 (rev. 1.0), socket AM3+
Memory: 3x 2GB DDR3 1333mhz (Total 6 GB)
Harddisk: 1x 250 GB SATA
Powersupply: Enermax EPM1500EGT Platimax, 1500 Watt
GPU: 2x XFX R7990 6GB

I hope someone got a solution for me.

Thank you,
Xeon

[juggalodarkclow]

Is the pc turning off or is CGminer turning off? If CGminer is turning off, what version are you using? FYI, no versions of CGminer past 3.7.2 support GPU's.

[TAZlitecoin]

Is the pc turning off or is CGminer turning off? If CGminer is turning off, what version are you using? FYI, no versions of CGminer past 3.7.2 support GPU's.

Hi, Im having the same problem./help plz...  My pc wont start up .  Everything works perfectly fine with 1 xfx r7990 but when I plug in the 2nd gpu my whole mobo fails after a few sec, restarts, and begins to run but does not give video output. Again works perfect with just 1 xfx r7990 but cant figure out why it wont accept the other...(or any gpu for that matter.  Have also tried the r9 280x with the same outcome)

my mining rig specs:

cpu- i3 4130
mobo- msi Z87 mpower max
memory- (corsair-CMX8GX3M2A1600C9) DDR3 1600 1.65V 4GBx2
Harddisk: 1x 500 GB SATA
PSU- (thermaltake) Toughpower XT Gold 1475W

with of course...GPU: 2x XFX R7990 6GB
like to connect all 3 utilizing each PCIe slot. (r9 280x as well  but fails just like the 7990)

plz and thank you for all help

[usao]

I also have 2x XFX R7990's and had this problem. Turns out that my Lepa G1600 PS has multiple 12V rails, and the cards are pulling more than the individual rails can handle. If I had a single 12V rail, this probably wouldn't happen in the first place.
By the way, I put a power meter on the AC line into the rig and found that a single R7990 card is pulling over 600W when mining over 1.2MH/s. Assuminng that both PCIE power connectors are evenly balanced, then 300W=12V*25A. So, each card needs approx 50A @ 12V.
Im looking for a new PS now, with the 1600W range, but using either 1 or 2 12V rails rather than the 6 rails that my G1600 has now.
Another option to consider is a stand-alone 12V@100A PS to power the PCIE power connectors on the cards, then using a 350W PS for the mobo. Still thinking about this option, haven't tried it yet. I think if I tie the grounds together it should work...
Thoughts?
Oh, forgot to mention that I have both cards running now, but at reduced MH/s so they don't pull as much power. Seems to be working, but not an ideal solution. Only getting about 800 KH/s currently per card...

[fenghush]

I'm running 2 asus 7990's with enermax 1350w platinum without any issues up to 1500mhs per card I can get more but they cut off once temps reach 95C I connected both cards on 4 different 12V rails also got them on usb based powered pci-e risers. PSU is drawing 1100W on 240V off the wall.
If you ever want to sell those cards, shoot me a PM I would pay decently.

[jgm_coin]

I had a similar issue after one of my shitty riser cables failed and shorted, which caused power supply failure.  Get a power supply tester or test a new PSU or try just running one card to know if its the PSU.  Hopefully you don't need to RMA your cards since they get into the OS but they may also be damaged.