
Originally Posted by
Mgutierrez33
Short answer: a reference card is one that is identical to the "reference" circuit board design that nVidia or AMD produce to show to the AIB (add-in board) partners when they go to make their own variant; it typically also has a "reference" cooler on it like the one you tend to see in initial advertising for the cards.
The Details:
This can be of benefit to you if you plan to water cool the cards at any given point in time since these will be the version sold the most, and water block manufacturers have to make blocks that cater to the greatest common denominator; too pricey to produce a water block for a card that only sells in tiny quantities. You also get a blower-type cooler design typically, which means that you will have an easier tome keeping ambient temps in your computer down since all heat is directed out the back of the case should you keep it air cooled.
A downside is that sometimes reference coolers are pretty bad, like the R9 series reference coolers that AMD had on the R9 290 and 290X: noisy and inefficient. If they're alright then they still tend to be louder than aftermarket solutions at the very least.
Custom PCB cards (like the EVGA GTX 980 Classified or the Asus Strix 980) have specialized voltage regulation and delivery, as well as a fully custom cooling solution and a custom circuit board layout to accommodate what is supposed to be a more premium product out of the box, but sometimes at the expense of the card not being compatible with full cover water blocks and occasionally exhibiting a noise known as "coil whine" (think electric white noise that doesn't sound quite like anything that is "moving," per say... like a ringing in your ear only scratchier). Coil whine is just something that higher end products tend to do because of all the power they tend to want to consume relative to their lower tier counterparts.
Custom PCB cards tend to come with higher clock speeds than a reference card, which will typically ship with OEM-based solutions. The likes of EVGA, however, will also ship reference-designed cards that DO have a factory overclock on them for added performance out of the box. This is done within the card BIOS by the manufacturer and typically involves more careful selection of the GPU cores for their product (this is known as "speed binning"). These cards are the more sought after solutions by many since they will be compatible with damn near any cooling solution you could throw at it and the card will tend to behave very consistently across the board for most users since there is less margin for error on these.
As for FPS in games... well that all comes down to clock speeds. Higher clock speeds within the same range of cards typically nets higher frame rates in games, barring any card-specific issues (the PowerColor PCS+ R9 290 was PLAGUED with black screen issues until they released a BIOS update for the card).
Go for the most powerful card you can reasonably afford and that your PC can power and go to town. If the 970's price is more your speed then that card will serve you extremely well for up to 1440P gaming. The GTX 980 will clobber 1440P gaming and even offer solid framerates with many titles running at 4K... though if you have a 4K capable monitor already then chances are you have the scratch to afford the 980 anyway.
This got lengthy I know, but I like to be thorough and not leave people wondering with short, overly simplified answers that do them no good at all. Hope this helped!