Computer shuts off at random times

[surmise]

So I built my very first computer and with help of computer hope people, fixed a crisis involving connecting HDD and CDD to one IDE port.

Everything works; Sound, video, CPU shows up correctly, etc. Except two things:

1. I put in 4 GBs worth of RAM, system only shows 3.25GB, why?

2. Computer shuts off at seemingly random intervals. I can't be too sure(mostly because I shut it off voluntarily after installing each devices(video card, audio, wireless adaptor, etc.) at what point this started happening. The time between boot and random shut off varies wildly -- Anywhere between 30 seconds(this often happens when I try to turn it back on right after shut off, but not always) and 45 minutes(longest it's lasted so far as far as i know). Occassionally, even if i turn it back on right away after a shut off, it lasts good 30 minutes before shutting off, leading me to believe that it's not an issue of simple overheating.

2.5 I read a topic regarding similar issue and it recommended downloading speedfan to see if overheating was an issue. This, however, doesn't help me much since I don't know what the "normal" temperature is. It currently reads:

Fan 1: 2411 RPM Fan 3: 2428 RPM
Temp1: 46C Temp2: 55C Temp3: -2C HD0: 45C Core0: 60C Core1: 60C

However, I've seen Core0 and 1 rise all the way up to high 90s, is that normal?

Any and all suggestions would be much appreciated



Here's some specs if they help:

PSU: Antec Basiq 500W
CPU: Intel Core2 Duo E8500 @ 3.16GHz 3.17 GHz
3.25GB RAM(shouldn't this be 4.00?)
Realtek High Definition Audio
ATI Radeon HD 4550

[hot dog]

With respect to some of your ram not showing up, you could have some of it allocated for video ram in CMOS....If you don't have a video card, your bios will automatically allocate some of your ram to video memory..  For instance, the computer I'm using right now has 512 MB ram and originally came with NO video card, so the bios assigned 32 MB out of that 512 for video memory, so I only had 480 MB left for OS, and other applications.... Luckily I found an old AGP card with 64 MB of video memory and once I installed it, it took over automatically as my primary video memory and the entire 512 MB of RAM went back to my OS...         If you DO have a video card, there may still be some RAM that is allocated in CMOS, so you might want to check it out

edit: when you built your computer, you did use thermal grease between the heatsink and processor, didn't you?  Have you varified if the fans are spinning all the time, when you power on the puter?

[surmise]

With respect to some of your ram not showing up, you could have some of it allocated for video ram in CMOS....If you don't have a video card, your bios will automatically allocate some of your ram to video memory..  For instance, the computer I'm using right now has 512 MB ram and originally came with NO video card, so the bios assigned 32 MB out of that 512 for video memory, so I only had 480 MB left for OS, and other applications.... Luckily I found an old AGP card with 64 MB of video memory and once I installed it, it took over automatically as my primary video memory and the entire 512 MB of RAM went back to my OS...         If you DO have a video card, there may still be some RAM that is allocated in CMOS, so you might want to check it out

edit: when you built your computer, you did use thermal grease between the heatsink and processor, didn't you?  Have you varified if the fans are spinning all the time, when you power on the puter?

The video card i have right now ( ATI Radeon 4550 ) says it has 520MB; I'm assuming it doesn't eat up additional RAM.. or does it. I have no idea how to check if some RAM is allocated in CMOS. Heck, I don't even know what CMOS is abbrev of.

When I built the computer, the thermal grease was already pre-applied on the heatsink. No additional grease was given(I've bought CPUs before and this was certainly a first). The fans are definitely spinning all the time and computer functions perfectly... until it shuts off randomly

[hot dog]

What CMOS stands for is irrelevant at this point, but to enter CMOS and adjust the settings, turn off your computer and power it on again, and when the very first screen appears (usually the BIOS version) you have an option to press F1, F2, or delete key, to enter CMOS set up (what key you press depends on the motherboard)... Once you are in CMOS, search around for something along the lines of "video configuration".....You should google for the BIOS settings for your motherboard make and model, each motherboard BIOS/CMOS is different..

Have you tried disconnecting the power connectors on the motherboard and reconnecting them, to help the connections?  Do you have another power supply that you can borrow of equal or greater wattage for a little while to swap in there, just to see if it corrects the problem?  If it works then give the power supply back to whovever it belongs to then all you need to do is get a refund or exchange.

How long has this problem been happening? 

[hot dog]

sorry, I seem to have missed were you said the CPU temp raises to 90 degrees...You should remove the heat sink of the processor, clean the old thermal grease off with alcohol (make sure it's very clean) apply a new layer....google for how to apply thermal grease properly

When you google for your motherboard settings, see if there is a way to adjust the fan speeds in CMOS...I'm not sure if fans speed up automatically (by default) in all motherboards when CPUs start to work harder, but you might check to see if there is something like that in your CMOS


edit: you should order some high quality thermal grease.

[Spoiler]

Your machine will never "see" all 4 gigs of RAM. If a machine is 32 bit it uses RAM in blocks that add up to a little over 3 gigs. This is normal. If you had a 64 bit machine you would be able to see the 4 gigs and more.

[Karnac]

You might also consider reseating your ram or try different slots.....Make certain the cooler/heatsink is flush to the motherboard all around.

[jerryheavyarms]

With regards to the RAM issue:

http://support.microsoft.com/kb/929605/en-us

[hot dog]

With regards to the RAM issue:

http://support.microsoft.com/kb/929605/en-us

this is great info! 

[neelchauhan]

Change the fans to more powerful ones. Quiet PCs will do this w/ air cooling.
If you need a quiet PC, use liquid cooling.