Dell Inspiron 3847 core i5 4460 - Attempting to Install EVGA GTX 950

System boots up, but there are heavy, snowy RBG artifacts (like little shimmering dots or pixels) on everything. I'm going from the Stock 3847 to the new EVGA GTX 950 SC (the short one). It also required a dedicated power source, so I got an EVGA 650 G2 (gold). The first graphics card showed this artifacting, so we took it to be a problem with the card and got a brand new one.

The new card did the same issue as the old one. I tested the new GTX 950 in a friend's really nice gaming PC, and it worked without artifacting. 

I tested the PCIe slot of my Dell with an old graphics card I had. The system was able to run off the graphics card without any artifacting.

We've tested the DVI and HDMI ports seperately. We've tested two separate monitors. 

EVGA support thought it might be the power supply, so they sent me a whole new one. We swapped out the psu and left the old cables. Same problem. We tried a separate individual VGA cable, no dice. 

We've gone to the EVGA website and downloaded the latest driver and performed a custom "clean" install. The latest driver is from 10/7. We've done this through the GeForce experience as well. 

We've downloaded the latest Dell BIOS. 

We've reseated the graphics card more times than we can count. We've even reseated the RAM. 
We've messed with manually disabling the drivers for the integrated graphics, both with and without the GTX 950 installed. 

The artifacting persists from the start of the Dell logo, is all over the desktop, ect. When I attempt to run a newer program like Borderlands 2, the artifacting intensifies and the screen begins to cut out. Here's the thing - it'll run Borderlands 1 at the low settings without ANY artifacting at all. 

Could it be something with power volting? Something with the vRAM (since the card begins cutting out when under more stress). Could it something with the BIOS? The newest one is from Jul 20th, but the GTX 950 didn't come out for another month. There are a couple different options under the UEFI boot, maybe that has something to do with it?

Could this card just be "too new?" 

Any help is greatly appreciated. This is my first and only experience with upgrading a computer and it is a nightmare. 

Thanks so much for the response. I've spoken with evga repeatedly, and the dudes were always nice. However, I've had two brand new gtx 950s with the exact same issue. I've also tested my current gtx 950 inside a friends computer with no issues. It seems like the problem MUST be on my end, right?

Awesome, thanks for the advice! Would this test in BIOS need to be done with the GTX 950 installed? Where do I find this information? The BIOS gives me 2 legacy boot options, 3 UEFI boot options (it's usually set to Legacy, does this matter?), and then BIOS set-up and diagnostic options. There's nothing about power or any other such details under the BIOS set-up, and I could only find CPU power stuff under the diagnostics. 

If this were the case, would the issue be a faulty PSU? I've also tried two of those, and the problem seemed only slightly less-terrible on the 2nd unit.
 
I'm thinking of just going back to the 300~w stock PSU and getting a GTX 750 Ti SC.  Would this issue persist if I'm just using this card of the motherboard power (no direct power connection). 

 
One of your last points is that a $50 dollar power supply is good idea. But if the $100 EVGA Gold certified G2 that I'm using now (and have tried a replacement of as well) has unstable voltages...wouldn't that mean the problem is with something on my motherboard that regulates power? 

So, my BIOS doesn't have that information. I downloaded a voltage monitoring program from CPUID and it gives me several voltages of several different components, all between 1-3v (and stable). The only value that is higher than those (that I can see) is an 11.9v on the -5v rail (or whatever the program calls it).  All voltages I can see are stable. 
 
I've also checked that PCie slot with an old graphics card I had, and there was no artifacting. It only has the one. 
 
Thanks for all your help on this, it really is baffling to everyone I've talked to. It seems like it might just be incompatible with the motherboard, but it's only a 1-2 year old system. That also doesn't seem quite right. 

It's mind-boggling that it just wouldn't be compatible on a firmware level or whatever! Like, this guy put a GTX 960 in his!


 
I really want the power and performance of the GTX 950, but I guess it's just straight up not compatible. Which is worrisome, because the reason I got the big expensive power supply was to facilitate more upgrades down the road. It looks like what I'll need to do is return the power supply, and run a GTX 750ti off the motherboard since I know for sure both the PCIe lot works and that's like the only card that doesn't require a dedicated PSU connection, and people have documented it worked on the 3847 mobo.