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Noticed something a little strange (Tahiti LE)

post #1 of 2
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Powercolor 7870 MYST. BIOS 0.28

As anyone who has one of these knows they throttle like crazy if you don't turn the Board Power Line up.

Mine artefacts at 1200Mhz or anything over, In Heaven 4.0 i get little speckles here and there and big purple / red flashing when passing the white chimney smoke over the roof top.

So i have been messing about with it to see if i can figure out whats going on.

To cut a long story short i realised that by only using 5% Board Power Line i get no artefacts at 1200Mhz and only very occasional throttling to 925Mhz, at 8% Board Power Line it sits solid @ 1200Mhz and i only get very slight artefacts, in fact the white chimney smoke over the roof top is the only place that it does it and is greatly reduced.

The more i turn Board Power Line up the more it artefacts (all GPU frequency and volts settings exactly the same)

Now i find that interesting, either the GPU chip is asking for more power that the rest of the GPU can provide and that rest of the GPU (PCB / VRM's) is overloading and causing artefacts.

Or the PCB is providing that power and its to much for the GPU chip. (I cant see that)

Or as with option #1 the PCB can't provide the needed power and is starving the GPU chip of power but is some how still able to keep going all be it with artefacts.

So... can the PCB's designed for these chips handle the cut down Tahiti core? is x6 pin power lines enough?
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Odd Ball
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post #2 of 2
Yes it's enough to run the card overclocked, almost all AMD gpus need their board power limit pushed up or they'll throttle a bit.

Go here for more information about your card, if you haven't already: http://www.overclock.net/t/1373543/official-7870-tahiti-le-xt-owners-club
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It's Black?
(18 items)
 
Clean N' Green
(17 items)
 
 
CPUMotherboardGraphicsGraphics
Intel Core i5 3570k TZ77XE4 Intel HD Graphics 2000 (GT2) PowerColor R9 290x TurboDuo 
RAMHard DriveHard DriveOptical Drive
Samsung Low Voltage Samsung 830 Toshiba PH3200U-1I72 Asus DVD R/W 
CoolingCoolingOSMonitor
Custom dual loop water cooling, one for gpu and... ApogeeCPU block Windows 7 64bit Asus VG248QE 
KeyboardPowerCaseMouse
Microsoft Sidewinder x4 RAIDMAX RX-1200AE Corsair Vengeance C70 (black) MW3 G9X  
Mouse PadAudio
Razer Goliathus Control Creative Recon HD  
CPUMotherboardGraphicsRAM
Intel Core i5 2500k ASRock Extreme 6 Z77  Sapphire 7950 GSkill Sniper 1333  
Hard DriveHard DriveHard DriveOptical Drive
WD Caviar Black WD Caviar Black Vertex 2 HP Light Scribe DVD RW 
CoolingOSMonitorKeyboard
Cooler Master Hyper 212 Evo Windows 7 64bit AOC 1920x1080 Rosewill 
PowerCaseMouseMouse Pad
OCZ Z Series 850W Modular NZXT Source 210 Pixxo Laser Razer Goliathus 
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Xi-fi Xtreme Music 
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