Decane

Hi all,

I've just built a new computer, so first off, here are the specs:

Motherboard: MSI P7N Platinum SLi (nForce 750i chipset)
CPU: Intel Core 2 Duo 2.2GHz 800MHz FSB
RAM: 4GB OCZ SLi RAM (800MHz)
GFX Card: EVGA GTX 260 Superclocked edition
HDD: Seagate 250GB
Case: Coolermaster Cavalier.

I recently built a computer for my younger brother, the specs of that are as follows:

Motherboard: XFX 680i LT SLi
CPU: Intel Core 2 Duo 2.2GHz (OCed to 3.5GHz)
RAM: 2GB OCZ SLi RAM (800MHz)
GFX Card: Gainward BLISS 8800GT GLH
HDD: Seagate 250GB
Case: iCute case from Maplin.

Now I ran a 3DMark06 test with the computers side by side, and the less powerful computer; my younger brother's, completely wiped the floor with my new system. Then I ran a Call of Duty 4 mission with the two computers side by side, and my computer beat the other one by 20 FPS average. However, it wasn't nearly performing as well as I've seen in benchmarks on review sites.

I suspected the CPU being a bottleneck for the GTX 260 graphics card... so I went about overclocking in the BIOS. Bear in mind I overclocked the same CPU on the other computer to 1.3GHz over it's stock speed. I raised the FSB from 800MHz to 820MHz, and I got no post at all. it just sat there with a blank screen. CMOS reset #1. I tried it at 810MHz FSB, and I got it to boot into windows with 2.22GHz on the CPU. A meaningless overclock.

The next time I decided to leave the FSB alone and try upping the RAM speed. This results in another bootless startup... I then go into changing voltages and trying again... not a sausage. I tried underclocking it, by decreasing the multiplier (which is at 11), and that boots up fine... but the aim of the game is not to <i>underclock</i> the system. then I try decreasing the multipliyer and increasing the FSB, still keeping the CPU below 2.2GHz. And again, I get no POST.

Intent on trying everying, I try overclocking within windows... at any attempt to increase the FSB, I get BSOD and have to do another CMOS reset. I've tried changing the memory timings and voltages to their recommended values... (4,4,4,12,2T - 2.1V) and it boots into windows, so long as I don't touch the FSB, or Memory clock frequency. (However, I soon found that these memory timings game me serious instability in windows, shutting down programs unexpectedly all the time - perhaps this was to do with that fact I had the frequency at 800MHz?)

I am currently suspecting a duff motherboard, and this is my last cry before I get the thing RMAed, and possibly purchase a different one.

Thanks for reading all the way through the post, and thanks in advance for any help you can offer,

Kindest Regards,

David.

Decane

Anyone have any idea?

lazareth1

800mhz? Dont you mean 400Mhz fsb? What is the stock setting for fsb in BIOS?

Decane

Yeah, 800MHz, but the CPU on the other PC runs fine at 1150MHz FSB.
400MHz FSB makes the CPU run at 1.1GHz. The multiplier is on 11x, which is as high as it goes.

The default setting in the BIOS is 800MHz FSB.

Cheers,

David.

lazareth1

As well as needing to increase voltages, you also have to tweak the GTL ref voltages to keep the system stable. I'm overclocking just now and it's a nightmare, but the more i understand the better it gets. being able to tweak the GTL ref voltage is key, as it lets you overclock and depend less on hiking up the voltages which produces more heat etc. Take a look here for more help on this:

http://forum.xcpus.com/overclocking/...ing-guide.html