I feel a little bad making yet another one of these topics, but I guess there's been worse fads on GDNet.

So my current computer has vuaultcli.dll error popups every time I start, semi-frequently BSoDs, takes 10 minutes to start up, and has occasional graphics driver issues (funky dead pixel swimming popping up arbitrarily sometimes), both VS and Windows are DreamSpark licensed (i.e. un-fixable, but thats totally fair since they were free and I'm not a student anymore), most of my hardware is five years old (except for my lovely 60GB HD which is closer to ten), and I don't take terribly good care of my PC in the first place. Worst of all, it can't even play some recent games (Watchdogs comes to mind)! I decided it's probably (really) high time I upgrade, and given the circumstance I've decided to do so mostly from scratch this time. For reference, my current hardware:

CPU: Core i5-750 (Lynnfield-era)

GPU: GeForce GTS 250

HD: 1 60GB Maxtor (10 years old), 1 120GB WD (7 years old), 200GB WD (5 years old), all HDDs.

PSU: 800-Watt OCZ

RAM: 4GB OCZ (2x2), 16GB Corsair (2x8, bought it last black friday)

Case: Super bog standard boring $40 case

Not in use: 250 GB SSD (bought it with the RAM; haven't used it, so it's as good as new)

I figure I'm gonna cap myself around $1500 -- hopefully enough to get a great rig but low enough to not go super crazy (avoiding stuff like silly SLI Titans). It's not a hard limit, however. I want something that can play anything on max settings for the foreseeable future. I've got a couple fixed things I know I'm going to want: 2 nice big monitors with DisplayPort support and this case from Hodgman's thread (I absolutely love the design and I'm sick and tired of having to take apart half my PC to install a freaking hard drive). Obviously, these two fixed points are going to cost a pretty penny over my usual expenditures, so would the remainder (probably about 1k I'm guessing) be enough to get something really nice but still relatively sane on the price/performance exponential chart?

I'm mostly looking for general advice for hardware, but if you like, some more specific questions:

1. I know the Haswell-E and X99 stuff came out recently. Are they worth the premiums, or still in "lawl early adopter" mode?

2. Likewise, I've heard current DDR4 isn't currently much (if at all) of an improvement over current DDR3 stuff. Is it worth jumping for the new standard, even if I have 16 gigs of DDR3 RAM lying around?

3. I know graphics cards take a lot less power than they used to. Is an 800W power supply even necessary anymore? I'm not looking for a crossfire/SLI setup or anything, as I don't think they perform particularly well in terms of price-efficiency, and I've heard horror stories about stuff not working with them well at all.

4. I'm totally out of date when it comes to GPU knowledge - which of the current-line gaming-class GPUs do you guys prefer, between the R7/R9 AMDs, and the 700-800 NVIDIAs? Having something that supports Mantle would be cool (especially if a public SDK comes out), but like 5 years ago AMD was horribly behind NVIDIA; not sure if that's the case today.

I'm definitely going to use the SSD for my windows install and VS/Programming stuff, and I'll probably buy a 2TB HDD for everything else just so I can say "screw it" for a while, since I've been constantly rotating my HD space for years. I want to use this rig for both gaming and non-professional development tasks.

If that 1500 is to also cover 2 monitors you are probably ganna be skimping on some of the pc parts to make it work nicely.

Is 1600x900 even a real resolution? What is that? WTFBBQVGA?

I've never seen it, but it makes sense given that most HD displays are 16:9.

Is 1600x900 even a real resolution? What is that? WTFBBQVGA?

1. I know the Haswell-E and X99 stuff came out recently. Are they worth the premiums, or still in "lawl early adopter" mode?

They're not worth it. I have one.

Don't misunderstand - it is blazing fast, able to support insane graphics and compute configurations, next gen PCIe, M.2, SATA express, all kinds of crazy stuff. But X99 is more workstation than consumer, and I consider it something you buy because you already know that you need that high of a spec. The big gains are 6+ core chips, huge memory configs (my machine is at 32 now and I expect to upgrade it to 96 next year), tons of PCI express lanes, that sort of thing.

Z97 and a mid range i7 is most likely where you want to be, given your price point.

2. Likewise, I've heard current DDR4 isn't currently much (if at all) of an improvement over current DDR3 stuff. Is it worth jumping for the new standard, even if I have 16 gigs of DDR3 RAM lying around?

DDR4 might have more bandwidth on paper. My experience is that this - as well as latency - makes no difference in real world applications, even intense ones. Total amount is far, far more important.

3. I know graphics cards take a lot less power than they used to. Is an 800W power supply even necessary anymore? I'm not looking for a crossfire/SLI setup or anything, as I don't think they perform particularly well in terms of price-efficiency, and I've heard horror stories about stuff not working with them well at all.

I think you'll be surprised to find that power supply output doesn't track cost all that strongly. Stuff like 80+ Gold/Platinum, or more robust rail configurations, are what make stuff expensive. At this point I'd buy 750+ just because it's easier than worrying about it.

4. I'm totally out of date when it comes to GPU knowledge - which of the current-line gaming-class GPUs do you guys prefer, between the R7/R9 AMDs, and the 700-800 NVIDIAs? Having something that supports Mantle would be cool (especially if a public SDK comes out), but like 5 years ago AMD was horribly behind NVIDIA; not sure if that's the case today.

This is a borderline religious argument and my religion is NVIDIA. Performance is generally comparable, with individual chips at individual levels being ahead or behind at random. I'd suggest checking TomsHardware/ArsTechnica/AnandTech or the like for a recent GPU buying guide.

My very personal take on the GPU issue is that I've had numerous problems with AMD's software -- and occasionally hardware -- in stability/reliability/features. My X99 machine is running two 7970s (of the very rare Eyefinity 6 variety), so believe me I'm not speaking from total ignorance. While NV has not been perfect by any means, my experience with them, particularly as someone doing a lot of OpenGL work, has been far more positive. This is exacerbated by incidents like the frame pacing fiasco. It's enough to eclipse the relatively unremarkable and inconsistent performance differences, for me.

In general, I'd say that the biggest improvements in the day to day experience of using a machine are: 1) lots of memory 2) SSD 3) CPU or GPU depending on what you're doing. Code builds do well with wide multicore; gaming prefers 4-6 fast threads. For SSD, the fact of having one is more important than the specifics, but I'd start with the Samsung 840 EVO or Crucial MX100. GPU is dependent on budget but for me it'd be all about the GTX 780. (I'm buying paired 980s, but that's the advantage of having an expensed work machine ;)

PS You may find PCPartPicker useful.