Replacement components for a computer that does not POST

Replacement components for a computer that does not post

My desktop computer has been exhibiting unusual behavior over the pass week. Unfortunately, my pc does not always post when the power button is pressed. Sometimes, the computer turns on after several hours. When the computer does not post, I cannot hear the drives spin up or any posting process (including beeps).

Unfortunately, my time is limited for researching and troubleshooting the situation since this computer is down. I have re-seated all the components inside the case, yet do not have additional components to swap in and out. The computer switch seems to work on the case. When opening the case and pressing the power button, CPU, graphic card, and case fans turn on. The paperclip switch technique did not make the computer post either (same effect as the power button). Changing the motherboard battery made no difference.

My initial thoughts relates to the motherboard or video card since the power supply is less than 6 months old (Corsair TX750W). When the computer turns on, it does not encounter any errors or hiccups; and performs as expected.

My first inclination is to begin looking into replacement components, yet I was not planning a major system upgrade. So I humbly request suggestions on replacing my motherboard, processor, and video card. My current system has processing power for most computing tasks except when doing heavy multi-tasking with streaming HD video. My requirements for replacement components would revolve on a dual monitor setup; moving large files, file archiving, and HD video decoding in a multi-tasking environment. This rig does not serve as a gaming machine. Value is a top priority for replacement components. My budget will be between $300 and $400.

AMD seems like the better value. The Phenom II X6 1090T looks good with 6 cores. The motherboard and video card are not easy choices. It has been 5 years since my last system build and the technology has rapidly evolved. The motherboard should have at least 6 Sata connection (most seem to have 4) and on-board sound. USB 3 would be nice, yet not essential. The video card should be powerful enough for basic photo editing and viewing HD content. I do have 4GB of OCZ PC2 6400 ram from a previous hot deal, yet it did not work under my current setup. Below is a short list of potential candidates for replacement component and my current system.

I am hoping this thread would begin a discussion on the components that offer the best bang for the buck. Any suggestions would help me avoid major disappointments with getting this system back online.

Update: The computer has not turn on in several days; it may be completely dead.

Replacement Components
-----------------------------------
Phenom II X6 1090T Black Edition
ASUS M4A89GTD PRO/USB3 AM3 AMD 890GX SATA 6Gb/s USB 3.0 HDMI ATX AMD Motherboard
XFX Radeon HD 4670 Video Card or something under $150

Current System
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Processor: Athlon 64 X2 4400+ (2.2GHz) 1MB L2 Cache Socket 939
Heatsink: AMD Heatsink-Fan: Thermalright XP-90C w/92mm Fan
Motherboard: A8N-SLI Deluxe
Video Card: XFX GeForce 7800 GT 256-MB PCI Express
Power Supply: Corsair TX-750w
Memory 2x1GB 400Mhz PC3200 DDR RAM 184PIN DIN
Monitor Dual Dell 22 Inch 2209WA
 
Take it to a respected computer repair shop, and find out exactly which component is failing. It might cost you $60 -$90, but will save you money in the long run.
 
You will need to replace the RAM also. The new motherboard uses DDR3 RAM.
 
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