So, I purchased a RMA Replacement 780ti Classified from a Forum user a while back, because it was a good deal and I want to try 4 way SLI with LN2, as well as use 4 GK110 Cards for folding.  
 
I just tested the it was ok.  Temps didn't go above 73, so not bad at all, right?  Well, time for the water block then.. I pull the cooler and see this:
 
 
 
The top right corner is completely missing thermal paste.  I experienced one BSOD right after Firestrke and didn't catch the code, but equated it to the 4.6 try on the 3960x and figure I should just add a little bit of voltage to make it ok.  
 
So, when I state that it doesn't hurt to pull the 5 screws and check the thermal paste, this is why. While typing this, I actualy notice the top right and top left both are void of TIM.  It never hurts to take the 10 minutes that it requires to check the thermal paste and make sure it wasn't applied incorrectly at the factory.
 
Now, on to sticking the water block on temporarily.  LN2 pots in the near future :-)

I have almost exclusively used Mx-4 on every gpu. I am starting to use Gelin Extreme and will be using that as I m0ve toward extreme cooling methods.

I am going to go looking for dry ice tomorrow.

That is indeed it. That little spatula is awfully handy as well. The only thing I spread Tim on is my gpu core, to avoid the possibility of air pockets like the ones above. I will share a picture of the results when self spreading.

 
Spread with Spatula:
 

 
 
After results from pulling block off.  The center is just from where I pushed down on the back of the card to help it spread.

 

that doesn't look good at all, about 25% of the GPU was not covered.
interestingly you didn't have unusual temperature increases, just luck maybe.

AWK16
This is only my opinion and opinions vary so take this with pinch of salt.
I personally would stay away from Gelid, this stuff is good for short period of time, unless you don't mind replacing it every 3-5 months. I had bad experience with Gelid not on one occasion but numerous of times....simply, it dries to the bone after short few months.
I'm not sure if that's true or just a rumor but I have heard that this product have been discontinued from production, some places selling them as clearance product to get rid of it. I emailed the company number of times, not a one response.
I think MX-4 is exceptionally good product, I would stick to something that has been proven to work, and I don't mean temporarily

Thanks for info. I am finding it on sale everywhere ATM.

void_ptr
TIM dries up with time. I had MX-4 on 4 Titan Blacks - applied when installing waterblocks; applied equally well to all cards. After a few months one card had core temps creeping up to +10C compared to the rest. Opened it up, and part of the chip was exposed. I reapplied all 4 and used Gelid GC Extreme this time around - so far so good (it's been 1 month), will see how it works long-term.

MX-4 is good for 8 Years.

void_ptr

bcavnaugh
MX-4 is good for 8 Years.

Has this claim been somehow substantiated or verified by someone?

Funny.

Keep in mind, whether we talking about PC components, electronics or everything else, at one point, most if not all of the companies would start out with very good products ( to gain customers attention) and only few would consistently produce the high quality product(s) they started out with without any degradation until today.
After while they  would start to cut corners in many different ways, ether stocking up products in warehouse and distributing to retailer way past the expiration date, obviously we talking products with expiration time or simply cutting on product quality right at the production line, simply put it, taking the silly way  to cut cost and taking customers for granted.
Getting back to Gelid..  Gelid use to be my primary compound I would buy a lot for myself, family and friends until I know this the quality became very inconsistent, in which just started recently last year.
When in 2011 I build my nephews PC I used MX-4 on 2 GPUs  and CPU, this year he got new machine so he took apart all of his old pc and that paste was still wet, now! that's impressive.
I used Gelid Extreme in number of my own workstations and for about 3-5 months time  the temperatures were exceptional and then started to go up slowly so when I decided to stripped apart one of the machines the compound was latterly bone dry.
I believe that at one point Gelid was exceptionally good compound, but that is not the case anymore, while MX-4 consistency in quality stays as good as it was years ago.
 

I like AS5 for my cpu. The only thing I am not a fan of is the cure time to get the best performance out of it.

I keep hearing about Shin through reviews, and I keep forgetting to grab some.  I will grab it on Payday so I don't forget again.

Generally I have used IC Diamond on GPU dies because I tend to not want to take them apart often.... & it works well on them
 
I use  MX-4  on all my cpu's  .... been pleased with it for years.

Update:  Received a 780 Classified this time, and found that the entire GPU Core was covered, plus a little extra, and that one of the thermal pads was only sitting partially off of two of the memory modules.  
 
Easy corrections, but it never hurts to check these things to make sure that they are correct.
 

 

 

 
 
 
 
This was the backplate from my 980 K|ngp|n from the factory:
 
 
 
 
 
I don't think any of these would have been harmful, honestly, but it never hurts to take a peek under the hood and make sure everything is clean.