First scratch build.

[Trigg]

I've just completed my first attempt at building a computer from parts I chose & found.  system is:

Case                 HP Pavilion  a1310y
power supply    300 W
OS                     Windows 7 Pro.  Build 7601
Motherboard     Motherboard   Acer E946GZ
Northbridge     Intel 946PL/GZ C1
Southbridge      Intel 82801GB (ICH7/R) A1
BIOS             Phoenix Technologies, LTD R01-C1 5\30\2007
Memory             2048 MB DDR2 SDRAM 667MHz
CPU                  Intel P4 672 Prescott 2M HT VT
                           3.8 GHz  FSB 800 MHz  TDP 115W  FSB factor 19
Audio                Creative SB Audigy 4
Video                Intel 946 GZ Express chip
Drivers             Main components are running latest supplier drivers for windows 7.  Many components                           are using Microsoft drivers.

I chose this system for cost and the desire to have the VT technology so I can run my old XP programs.
My problems are that the system hangs, games run with many pauses, a lot of programs run then freeze and the CPU fan runs on high speed much of the time.  CPU core temp. runs 59C.   Max is listed at 119C
The board will take 4 MB of memory.  The heat sink is rated for a 3.8 GHz CPU. 

Where did I go wrong & what do I do next?

[camerongray]

What sort of games are you running on it - That is a very old system that would struggle to run Windows 7 well, let alone games, especially since you are using the integrated graphics.

Is that CPU temperature under load or at idle?  What do you get under load?

[Trigg]

I know it is an old system.  It met the minimum requirements for Win 7 and has the VirtualTechnology I wanted to run Win XP programs easily.  & I got the components cheap.
   Sooo, the CPU temp as measured by "open hardware monitor"  runs 36-38C at idle and 58-59C max.  I don't know about spikes.  The fan goes to 5600 rpm at 58C and cools it. 
   I run old games.  Diablo II LOD and Battlefield 1942 mostly.  Still, running a youtube video will heat up the cpu.  According to a load calculator I ran, 300 Watts is enough power. Would more memory help?  I have 2X1Gb  KINGSTON pc5300 667 mHz  memory cards now.  I can go to 2X2Gb. 

[camerongray]

Those temperatures are fine, the PSU is also fine assuming it is a decent quality unit.  May be worth testing your hard drive, if it has issues it could explain random lockups.  Running a full memtest would also be worth doing.  More RAM could help but only do that if you already have it, don't go spending any money on such an old machine. Beyond that you may just be expecting too much from it, it's a Pentium 4 after all, at least 10 years old.

[Trigg]

I didn't spend more than $30 on any component.  About $140 total.  I could get a socket LGA 775 Pentium D or Core Duo2. for around $50.  I haven't researched their specs.  I don't think either have the VT technology. Wait a second, Wikipedia says that the core duo2 has VT in some cases.  I need to do some research. 
Thanks for your comments, camerongray.  I really wanted some assurance that I hadn't made any huge mistakes assembling this system.   BTW, a friend gave me his old a1310y to experiment with.  It was pretty basic, but 5 years newer than my Gateway 500 XLS Yorktown.    My real mistake was to use very old components when I was starting from a a case & psu..

[DaveLembke]

800Mhz FSB Core 2 Duo is about as fast as you will be able to push this board and thats assuming that the BIOS has the latest Microcode to support the better Core 2 Duo's etc.

I wouldnt spend too much money on this, but you might be able to get a Core 2 Duo E4700 with 2MB Cache that runs at 2.6Ghz which benchmarks much stronger than that P4.

Here is benchmark of the Core 2 Duo E4700 which might be supported by your board based on info at Tomshardware: 
http://www.cpubenchmark.net/cpu.php?cpu=Intel+Core2+Duo+E4700+%40+2.60GHz

Here is your existing P4: http://www.cpubenchmark.net/cpu.php?cpu=Intel+Pentium+4+3.80GHz

Here is a similar article to CPU upgrade that someone else wanted to go with a Core 2 Quad, but was shot down on Core 2 Quad because core 2 quads start at 1066 FSB, however Core 2 Duo with 533 or 800Mhz FSB may work. http://www.tomshardware.com/forum/268225-28-specs-acer-e946gz-motherboard

Here is a CPU on ebay for like $20 that is a cheap upgrade, but no info found on CPU support for the Acer motherboard. http://www.ebay.com/itm/Intel-Core-2-Duo-E4700-2-6GHz-2MB-800MHz-SLALT-LGA-775-CPU-Desktop-Processor-/291433078543?pt=LH_DefaultDomain_0&hash=item43dac3df0f

What games or software or application9s) do you have for an old computer like this? We might be able to help you avoiding wasted money if you expect to run something that this is not capable of, such as a person who asked me why Witcher 3 wouldnt run on their computer and come to find out there computer was almost 10 years old and the game requires a somewhat modern high end system to run the game etc.

[camerongray]

I didn't spend more than $30 on any component.  About $140 total.

I'd take this as a lesson to continuously think about what you are building, how much it is actually worth and what you could get for the same price.  $140 could easily get you a used i3 or almost even an i5.  You may want to consider selling the parts you bought on again and put this towards a better system - It's very often cheaper to buy a used machine as a full system instead of building it yourself, especially since you aren't doing anything that special with it.  Businesses are constantly selling off their systems extremely cheaply.

I'd cut your losses and stop spending more on that aging system - If I'm totally honest, a system with those specs is probably worth less than $50 on the used market.