Overclock fine at 2 gigs, can't get to BIOS at 4

[TwistedJester]

First my setup:

Core 2 Duo E4500 (OC'd to 3Ghz)
Gigabyte DS3-L
2 gigabytes of G.Skill RAM
Radeon 4870 512MB
XP Pro

My set up has been the same for the past year (except getting the 4870 a few months back, but I highly doubt that's the issue), and this overclock has been very stable until just now. I'm looking to install Vista so I can bump myself up to 4GB of RAM, so I bought another 2x1GB set of the same G.Skill RAM that I'm using now, which I bought a year ago. However upon putting it in, my system sets itself to the stock CPU frequency at startup. I can't even get to the BIOS before it resets itself. If I remove the two sticks in question, the overclock works fine.

So my question is, where should I start looking to tweak to try to get this overclock to work? And would I have been better off just getting a matched set of 2x2 GB sticks?

 

[sirmonkey1985]

pretty normal problem when running 4 sticks of ram.. problem is the same with intel and AMD.. drop your overclock to 2.8ghz see if it will boot up.. the problem doesnt mean you cant overclock.. just usually means you cant reach the same overclock you did with 2 sticks of ram.. your best option is to get 2x2GB sticks so you can keep your 3ghz overclock..

 

[BillParrish]

So my question is, where should I start looking to tweak to try to get this overclock to work?

A fairly large increase in MCH voltage and a small increase in FSB voltage (do not change both at same time, try increasing MCH voltage first +.1 +.2 +.3 without a fan on the MCH I would not go much above +.3 but many run MCH voltage very high without issues. Just depends on your MCH and how good the heatsink is contacting it and case airflow etc. etc. Glue a 40mm fan onto it with silicon RTV.

I would also right from the start give the memory voltage ( Vdimm) +.2 (total 2.0V) even if they are not OCed and if at +.3 on the MCH was not stable consider a try or two at memory voltage +.3 (total 2.1V) to see if it helps. (At a memory voltage of +.3 I would boot a memtest86+ CD and let it run a full pass of all tests and stick my finger on the side of a stick and access the temp and decide if they where running too hot and if so consider a spot fan or some other means of getting air to the sticks as the middle ones will get even toastier than the outer one you can get your finger on.

And would I have been better off just getting a matched set of 2x2 GB sticks?

Yes. Typically they are easier to OC but 4 sticks installed is not as much of a OC killer on these newer boards. Still you may have to be creative with timings etc.


If I recall correctly you have an 11X mulitplier, I would be using that to keep the FSB low along with the 2.0 memory mulitplier to keep the memory running under its rated speed until I found out what the cpu would do.



Keep in mind this is a budget board and over stressing the CPU voltage supply MosFETS which have no heatsinks and the filtering capacitors with poor case airflow or replacing the stock intel heatsink with one that does not blow air on the components around the cpu socket might reduce the life of the board.

 

[TwistedJester]

I bumped up the voltage on the MCH and that seemed to do the trick. I also glued a 40mm fan to it when I first got the mobo about a year ago. I'm actually pretty sure I did so after you mentioned it in another thread.

Thanks a lot for the help.

 

[koei]

with 4 stick you are putting much more stress on the NB memory controller, so it's not unusual that it has hard time booting with overclock.