A friend of mine wanted me to make a build for him that would allow him to play Dolphin and PCSX2 at full speed 1080p. He was getting a new PC anyway for web-browsing, school, and as a media device, but he asked if it were possible to build something under $600 that would play Dolphin/PCSX2 in addition to some low-level games (LoL and MMORPG's mostly.) I'll share it here for those who are interested. 

The total cost without the OS, Keyboard, Mouse, and Optical Drive (if you want to include one) is $482.91 after rebates (which add up to $55.00.) 

PCPartPicker part list: http://pcpartpicker.com/p/83P399

Price breakdown by merchant: http://pcpartpicker.com/p/83P399/by_merchant/

CPU: Intel Pentium G3258 3.2GHz Dual-Core Processor  ($62.99 @ NCIX US) 

Motherboard: ASRock Z97M Anniversary Micro ATX LGA1150 Motherboard  ($74.99 @ Newegg) 

Memory: Crucial Ballistix Sport XT 8GB (2 x 4GB) DDR3-1600 Memory  ($59.99 @ Micro Center) 

Storage: Western Digital BLACK SERIES 1TB 3.5" 7200RPM Internal Hard Drive  ($69.98 @ NCIX US) 

Video Card: PowerColor Radeon R9 270X 2GB PCS+ Video Card  ($143.98 @ Newegg) 

Case: Fractal Design Core 1000 USB 3.0 MicroATX Mid Tower Case  ($35.99 @ SuperBiiz) 

Power Supply: Corsair Builder 500W 80+ Bronze Certified ATX Power Supply  ($34.99 @ NCIX US) 

Total: $482.91

Prices include shipping, taxes, and discounts when available

Generated by PCPartPicker 2015-03-21 16:20 EDT-0400

He can always upgrade his CPU to an i5 Haswell or Broadwell, in the future. The motherboard should overclock his Pentium G3258 by 30% with a click of a button, making it one of the best CPU's for Dolphin/PCSX2 and the CPU won't bottleneck the games he wants to play. His GPU is also capable of playing almost all intensive games if he wants to at good resolutions, although for future games he might want to upgrade his CPU, as they become more multi-threaded. Everything fits fine, although the card is cutting it close to fit without removing some HDD slots. He prioritized a smaller case, so I went with a Micro ATX board. He specifically mentioned that he's not intrested in an SSD (currently) if it's going to cost $100 more, so I opted out of that.  We get free operating systems at our college, so all he needs to do is buy a keyboard, and mouse and he's good to go. 

I would recommend an i5-4690K instead of the Pentium G3258 ...

Those emulators and can take advantage of a minimum of 3 or more cores ...

Dolphin only uses two-cores maxed. Check the benchmarking threads on  Dolphins forums. G3258 at 4.5-4.6 ghz is only bested by i7's overclocked to 4.9-5ghz. 

https://forums.dolphin-emu.org/Thread-unofficial-the-unofficial-dolphin-benchmark-results-updated-mar-18-2015

PCSX2 does use three cores for some settings, but again the difference is minute. 

Decent build, but go with i5 - last time I was checking, both of those emulators can use up to 3 cores, possibly more in latest versions.

In Dolphin the only setting which utilizes 3 cores is if you enable the DSP on an exclusive thread. Most developers said they'd need to do a lot of work to implement more features which would take advantage of multi-threading (the Wii's CPU was single-core/single-threaded.) They're asked quite frequently with people who have mobile i7's. Considering it would cost at least $150 more for an overclockable i5, for no performance gain (i5's and G3258 at the same clock speed perform similarly) it would make no sense unless he wanted to play future PC releases. 

PCSX2 has some hacks which use more cores, but again the marginal price/marginal performance is way too high, and one can easily play most PS2 games at 1080p on a G3258 with 4 x AA. 

I highly reccommend getting an Athlon x4 750k or an FX-6300 over that Pentium. Modern games no longer work anymore with dual cores and I guarantee you will want to play a modern game with a set-up that strong at some point.

Neither of the processors are as great at Dolphin (even when overclocked) though. I'm unsure how they perform for PCSX2. My friend is not a PC gamer other than he likes MMORPGs. But if he does become a PC gamer it literally is an upgrade away to an i5k, and he can emulate games just as well. Currently, the only game which doesn't work on an G3258 is Dragon Age: Inquisition, and the upcoming beta patch has fixed that. Future games likely won't work though. 

Dolphin can actually use 3 cores, one for emulating the CPU, one for handling the GPU, and one for emulating the sound DSP ...

The difference for utilizing 3 vs 2 cores in PCSX2 is NOT minute! The Multithreaded VU1 hack can provide significant speed ups from 3 cores ...

The DSP setting is not worth $140. As I showed, the G3258 has performance similar to an i5k in Dolphin. 

Super Mario Galaxy 2

https://www.youtube.com/watch?v=ki-Dq24iXBg

As for PCSX2, while there is a gain with the VU1 hack, again my friend is on a budget. Games like Shadows of the Collosus and Zone of Enders run full speed on the G3258@ 4ghz, and they're some of the most intensive games to run. 

Shadow of the Collosus

https://www.youtube.com/watch?v=HcO008UHets

^ Also it is only using 60% of each core. 

Actually, OpenMP Texture Decoder uses available cores, if there's any.

But given that you figured it out all by yourself, not sure what was the purpose of your thread, tbh - yes, that CPU is adequate. i5 is just better.