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System unstable - is it the standard BIOS setting?

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Last response: in Systems
a b B Homebuilt system
February 19, 2010 10:19:53 AM

I am by no means an expert but I thought I knew enough to put together a new PC. ofcourse I don't, and the system is unstable (freezes up when trying to run memory hungry games). The system is made up of:

Processor(new): Core i5 750 LGA 1156
Motherboard(new): GIGABYTE GA-P55M-UD4 LGA 1156
RAM: 2x 2gig DDR3 (in slots 1&3)
HardDrive(3yrs old): samsung SATA 3gb/s 250gig (in SATA2_0 slot running in IDE mode in BIOS)
DVD(3yrs): SonyDVD/RW in serialcable connection (not SATA)
PSU(3yrs): 600w ATX (has more than enough correct connectors for system components)

I am thinking the problem is either my PSU has lost efficiency and so cannot handle the loads, or the Gygabyte BIOS system default settings are wrong for the system (I have left it as it is apart from turning on the 64bit mode whilst installing windows 7 64bit). maybe voltage setting for RAM/processor clock speeds?
As mentioned I am no expert and not sure how/if I should change any settings or get a new PSU?
Any tips/advise welcome!

More about : system unstable standard bios setting

a b B Homebuilt system
February 19, 2010 10:46:59 AM

Forgot to mention GPU: Zotac GTX-275 896gig PCI-E !!
a c 84 B Homebuilt system
February 19, 2010 1:44:30 PM

We need to know the exact RAM model to help. It will also help to know the exact PSU.

Freezing is most often caused by problems with the RAM. If it was the PSU, the system would just turn off, it wouldn't freeze. However, before we test that, go through EVERY step of the "Read before posting about boot problems" sticky at the top of the forum. DO NOT SKIP any steps. EVERY one has a purpose to help troubleshoot the problem. Once you're done EVERY step, come back with any changes/results. Then continue with the following.

While it's probably not an overheating CPU, it doesn't hurt to check it, and you'll have some time to kill before the next step. Download Prime95 and Real Temp (or another CPU temp monitor). Run these two together for over an hour. Come back with the base temp and the maximum temp.

Finally, go to and download the ISO file of MemTest86+. Burn the image to a CD. Then restart and enter BIOS. Set the RAM to the manufacturer's specifications (match them exactly). Then set the computer to boot from the burned CD. Reboot and let MemTest86+ run overnight. This will test the memory completely. Once that completes (assuming there aren't any errors), try seeing if the problem is still there. If that doesn't fix it, come back with any results.
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a b B Homebuilt system
February 19, 2010 2:17:04 PM

Right, I'm off home to do as you say! Thanks for getting back to me on this - was just about to get a new PSU after work!
The Ram is 2x 2GB PC3-12800 DDR3 1600MHZ DDR3 CL 7 but I don't know the manufacture. Will let you know after done the step-by-step sticky as ordered.
a b B Homebuilt system
February 20, 2010 9:11:47 AM

Thanks for the tip - I now know where to look for idiot guides (top of forum) for my problems.
I set the CL to 7-7-7-28 in BIOS as stated by a manufactures but it also recommends the voltage to be 1.9.
Removed and had a good look at the DDR3 sticks, but there are no markings on them what so ever apart from the specs that the guy from Ebay put on the ad where I bought it from!
The Bios settings comments (in red) that 1.9 can damage the hardware so I set it to 1.7 (in pink) and the system has finally stopped the freezing-up.
Can I leave it at 1.7v or would you reccomend putting it back to standard 1.5v as the CL figures were the real culprits for making the system unstable? Or just ramp it up to the 1.9? As far as I can tell 1.9v is reccomended for DDR3 units of the same specs as mine (2GB PC3-12800 DDR3 1600MHZ DDR3 CL 7)?
Thanks again!
a b B Homebuilt system
February 20, 2010 9:14:55 AM

make that CL 7-7-7-18
not 28. sorry