Don't know if it's the beginning problem but the video card, according to the newegg site description, says System Requirements - A minimum 300W or greater system power supply (with a minimum 12V current rating of 22A) for your PNY geforce gt 430 (2gb ddr3) and you only have a 250 listed. Probably not be enough to run your system and might have started failing earlier causing the initial problem in the first place. If it is the original psu in a standard built hp or dell they usually don't give you a top of the line psu. Something like this Antec EarthWatts EA-500D for $60. Something that has the 22A on a rail for the card. Or THIS ONE CORSAIR Builder Series CX430 V2 (CMPSU-430CXV2) 430W ATX12V v2.3 80 PLUS Certified Active PFC Power Supply for only $25 after MIR
If the power supply wasn't the problem, I would definitely agree the RAM is the most likely suspect. Especially if you have a mismatched set, and ESPECIALLY if you have all four memory slots filled.
I wish I knew the specs of the stock RAM, but basically, here's what could be happening - in a system with four memory slots, if you fill all four, sometimes they requite a tiny bit more voltage (0.02V-0.1V) to run smoothly, and the "auto" setting won't cut it. So you have to bump it up a touch manually or you'll get freezing from undervoltage.
I'd say the simplest and safest solution for you - especially since you don't feel comfortable messing with the settings if you can avoid it - is to take out the two sticks of stock RAM, and use ONLY the PNY sticks (moving them to the slots previously occupied by the others). You could also keep ONLY the stock sticks, but if this is a prebuilt machine from HP or Dell, the PNY sticks are probably better.
It will not hurt you at all to go to 4GB; that's all games use anyway. Unless you do heavy-duty graphic design, video editing or something like that, 8GB won't give you any extra performance.
Anyway ... if you do that and the problem stops with just two sticks, you've found your answer.
To change the voltage, there should be a setting in the BIOS; its name will vary from one motherboard maker to the next. Could be something like "DRAM timings," "Memory manager," "DIMM channel settings," or it could be under an overclocking menu if you have that. Would really have to know your specific motherboard to tell you which.
But basically, you will see an option for manual/auto or enabled/disabled and a bunch of grayed-out numbers underneath like 1.50V for the voltage and 9-9-9-27 for the timings. So enable manual settings, and then bump up the voltage by the smallest it will let you, usually .02 at a time, until you get it stable. 1.5V, 1.52V, 1.54v, etc. If you get up over 1.6V, you probably want to stop and reassess.
But seriously - read the motherboard manual and KNOW WHAT YOU ARE DOING and what each BIOS setting means before you change them. Your memory can take an extra .1V or .2V in the short and medium term, so you're not likely to burn it out. But if you just bump around blindly and accidentally change the wrong setting, like the CPU Vcore voltage where a small change makes a huge difference, that's how you really wreck your computer.
So - try it with 2 sticks first to see if that's really the problem. In the future, if you want to use all four RAM slots, yes, it's best to get a matched set, or at least two sets with identical specs. But before you even think about upgrading to 16GB, I'd make sure you know how to solve this problem, and learn a little more about timings, speed, latency, voltage, so you know what to look for.
Also, unless you're running Windows XP, don't bother with a registry cleaner. They do more harm than good these days on Vista and 7. Don't trust software power monitoring; the only way you can get remotely close to what's really going on is with a multimeter.
ok, next maybe it's time to test the memory sticks themselves. Not using the Windows tool - using memtest86+, which will check every sector. Test it with one stick at a time in the machine, preferably with multiple passes on each, until you've gone through all four.
That's the site where you get it. It's not a traditional program that you download and run from Windows - you need to download the bootable ISO file and burn it to a disc with an ISO writer (of which there are many free ones). Then boot the machine with it like you would with a Windows disc - that is, set the boot priority in the BIOS so your DVD drive is first, then restart.
This could take a few hours overall, but if there's a problem with one or more of your sticks of RAM, this is the most likely way to catch it.
This does still sound like it's a likely RAM issue. In fact, if it happens more quickly with the two original sticks, I'd guess it's most likely the problem is with one of those, so perhaps that's the best place to start with memtest.
Also, did you try removing just the pny memory and seeing if you had trouble with just the original memory? As capt_taco mentioned earlier about removing the original sticks - "is to take out the two sticks of stock RAM, and use ONLY the PNY sticks (moving them to the slots previously occupied by the others). You could also keep ONLY the stock sticks, but if this is a prebuilt machine from HP or Dell, the PNY sticks are probably better. " Even though the pny sticks are better they might be causing the issue. Sometimes you just get a faulty batch after a little use.
I'm sorry, what I meant to say was to put just the 2 original sticks in and try to use your computer normally and see if it continues to freeze on you. Of course, personally. I still think it's the power supply due to the sound coming out of the speakers. Some sort of short in it, the mobo or between the two.