HD 5870 Not functioning correctly.

[hftvhftv]

I recently traded some old PC parts for an XFX 5870 and it didn't work 100%, artifacts would show up during a furmark test (maxed out at 75C). So I tore it apart, applied new thermal paste, and put it back together. Worked great, but I needed to take it apart again since I didn't place the plastic shroud back on so I could feel the heat pipes on the side to feel how hot they were. So I put it back together, cleaned the paste off, reapplied new paste, and put it back together. Now the card is producing artifacts again. So I take it apart clean it up, and bake it at 385F for 8 minutes, let it cool off, put it back together. Now the card doesn't even wan't to boot, my VGA_LED is illuminated. I felt the card after I turned off my PC and it was warm as if it were idling, and the fan speed was normal. So after letting it cool off, I restart my PC and it boots, but with the artifacts worse than ever. So I tear it apart, and I notice on the GPU die, there are small transistors next to the core, and I had gotten paste in between then when cleaning it up. I used some Chinese silver paste, so I'm thinking oh shoot, I may have shortened it. Should I bake it again? Or what else could I do? My PC specs are the following:

- FX 8350 @ 4.7Ghz, 1.5v

- Asus Sabertooth 990FX R2.0

- Seasonic X-850 watt power supply

[hftvhftv]

Don't run furmark... 

Also what temps?

The min was 40C, and it topped out at 75C last time I used it, now I can't get it to function. And on the VRM heatsink the thermal pads were leaving this moist residue, so I removed the pad, and there were about the same consistency of gum. 

[hftvhftv]

Never remove the pads unless you're replacing them/putting back again.

How much time did you run the GPU with load w/o the pads?

About 1 minute, but the card would not work anyways, with or without the pads. I replace the pads with a dab of thermal place on top of the plastic contact area to replace pads.

[hftvhftv]

I've re-read it again.

First of all: how did you position the card in the oven?

2-Are you sure that "chinese silver paste" is actually "real", are you sure it's conductive? bc then the card wouldn't even boot for a second.

Oh yes I'm sure it is, it is quite shiny, and it worked just great on my 1.5v 8350. 

[hftvhftv]

And I placed it on a sheet of tinfoil with the core facing up.

[hftvhftv]

It functioned for a little while after the baking, now the VGA_LED stays on.