mobo:  ASRock 970 EXTREME3 AM3+ AMD 970 SATA 6Gb/s USB 3.0 ATX AMD Motherboard    -  $85 now  (newegg.com price $75, 10/17/2012)

support:

   RAM -  DDR3 2100(OC) / 1866(OC) / 1800(OC) / 1600(OC) / 1333 / 1066 / 800

   970 Extreme3.UserManual.pdf

CPU:

(1) AMD Athlon II X4 640 Propus 3.0GHz Socket AM3 95W Quad-Core Desktop Processor ADX640WFGMBOX     - $80, 12/2012 - Note: not Phenom II X4

(2) AMD FX-6100 Zambezi 3.3GHz Socket AM3+ 95W Six-Core Desktop Processor FD6100WMGUSBX  - $105, 12/2012

(3) AMD FX-4170 Zambezi 4.2GHz (4.3GHz Turbo) Socket AM3+ 125W Quad-Core Desktop Processor FD4170FRGUBOX  - $120, 12/1202

(4) AMD Phenom II X4 965 Black Edition Deneb 3.4GHz Socket AM3 125W Quad-Core Processor HDZ965FBGMBOX - $100, 12/1202

(5) Intel Core i5-2500K Sandy Bridge 3.3GHz (3.7GHz Turbo Boost) LGA 1155 95W Quad-Core Desktop Processor Intel HD Graphics 3000 BX80623I52500K - $220, 12/1202  (K for unlocked)  (has integrated GPU)

(6) Intel Core i5-2380P Sandy Bridge 3.1GHz (3.4GHz Turbo Boost) LGA 1155 Quad-Core Desktop Processor BX80623i52380P (No integrated graphics so no waste on GPU) - $195, 12/1202 (95W according to cpu-world.com) (Introduction date: January 29, 2012 )

In fact, the review of FX-6000 series is not good, compared to Athlon Phenom II X6 1100T.  But for such a low price, the performance/cost ratio is still very good.  But compared to Athlon II X4 640, it may even slower (src : The Phenom II X4 945 and Athlon II X4 640 are a bit slower than the 4170 (the older architecture of the Phenom II and Athlon II is much faster, but those two in particular would be slightly slower) and the 6100 is a lot slower. )

And "Athlon II X4 640 does not have a L3 Cache." (src)  But for reusing my 485W PS, better to pick Athlon II X4 640 for safe side.  965BE & 4170 are better for gaming but it doesn't matter to me.  An feedback: "ASRock K10N78D motherboard: selected auto core calibration and it unlocked the L3 very nice;  also did safe oc to 10% and runs at 3.3ghz "

Vishera review (highlight: AMD's six-core FX-6300 not doing well, never buy it!)

"X" is for our Extreme Edition top of the line processors. 
"K" is for unlocked and able be overclocked easily. 
"P" is for no IGP (Integrated Graphics on Processor) 
"S" is a low power processor 
"T" is a very low power process that is designed for thin form factor cases and boards. This of this in an HTPC.   src
And "M" for mobile/notebook CPU.

 

RAM:

1. DDR3-1333 is better (newegg.com price $17) - Crucial 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1333 (PC3 10600)  BLT2KIT2G3D1337DT1TX0

Note: CL=7 (7-7-7-24) is better than CL=9 which is probably on the HP Pavilion p6-2378 Desktop PC, I guess.  I remember reading from somewhere that CL7 1333 is better than CL9 1600.  More on it:  <1>   Review at newegg

2. Crucial Ballistix 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1866 (PC3 14900) Desktop Memory Model BLT2KIT2G3D1869DT1TX0 - CL=9 ( 9-9-9-24 ) , 1.5V - newegg.com price $20  No ECC, Unbuffered.                                                                                                                                                                   BLT2KIT2G3D1869DT1TX0

Note: (1) Had to manually set speed (1866) and voltage (1.5V) in BIOS.  (2) have to enabled the AutoOC for some MB. (3) According to crucial.com, it is compatible with above ASRock 970 EXTREME3 AM3+ AMD MB.

 

PS:

COOLMAX ZX Series ZX-700 700W ATX12V v2.2 / EPS12V v2.91 SLI Ready CrossFire Ready 80 PLUS Certified Active PFC Power Supply - newegg.com ($39.99 after $10.00 rebate )

 

Case:

Antec Three Hundred Black Steel ATX Mid Tower Computer Case (newegg.com: $59.99) (Amazon.com: $54.99 + Tax = $60)  manual

Antec 300 Illusion

Review: YouTube-1   YouTube-2   Newegg TV: Antec Lanboy Air Test Build with 15 Fans


Existing components which are reusable for the new PC:

Case:  GIGABYTE 3D AURORA GZ-FSCA1-ANB Silver Aluminum

                              ATX Full Tower Computer Case

                          - http://www.newegg.com/Product/Product.aspx?Item=N82E16811233001

                          - review: http://www.xbitlabs.com/articles/other/display/gig-3d-aurora_12.html  - 10/01/2005

PS:  ENERMAX Noisetaker II EG495P-VE ATX12V 485W Power Supply 115/230 V - Retail

      - http://www.newegg.com/product/product.asp?item=N82E16817194009

                          - http://www.buy.com/prod/ENERMAX_Noisetaker_II_EG495AX_VE_SFMA_485W_ATX12V_Ver_2_2_AC_Power/q/loc/101/203169725.html

                          - http://www.xbitlabs.com/articles/other/display/psu-roundup.html  - 02/28/2006

Video card:  Radeon HD 5450

USB + 1394 bracket: possible

OS:  Win7 32bit


Old components from others or my inventory:

1. Real Power 230P ATX Computer Power Supply 20 Pin (230W) - info-1


According to here,  I only need 350W (forget to add 6 USB devices) 365W PSU is good enough for 95W CPU :

power supply calculator


Koutech USB 2.0 Header-Pin to Dual Type-A Adapter

amazon.com   newegg.com

Converts an external usb port into TWO internal ports. Simply unplug the motherboard connection to one of your computer's unused usb ports (a front port for most people), and plug this to your motherboard to give your computer TWO internal usb ports. Use one for a Bluetooth adapter, and the other for a flash drive or wireless adapter. So now two usb devices are secure and out of view.
What's with the description saying that it works with Microsoft Windows 98SE+ and Mac OS 8.6? We know Windows is made by Microsoft, but thanks for reminding us. Both those OS's are ANCIENT, and nobody uses them. Would be clearer to simply say that it requires no software, so works with all operating systems.


VANTEC UGT-IH100 Multi-function Front Panel USB 2.0/FireWire 400/eSATA x 1
http://www.newegg.com/Product/Product.aspx?Item=N82E16811999231  (read review b4 buy)
 - Seamless integration in any standard 3.5"or 5.25"
 - 5.25" Bracket Is Included
 - Multi Front Panel Hub: Front USB 2.0 Ports x 4 FireWire 400 Ports (4 Pin and 6 Pin) x 2 eSATA Port x 1
 - Plug And Play – No Drivers Are Required 

Questions:
(1) How many free USB headers do my old PC have?

WiFi adapter

Mouse (optional)

Better keyboard (optional)

SATA cable with metal latch 18"