Question on Ram - Wont boot with 4gb?

[Andeh13]

My system is to the left and i was thinking of adding another 2 sticks of ram. The ram is spare from a PC i built my sister so im only asking if it will work or not.

Currently i have 2 x Corsair TwinX XMS2 of:
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and the ram iv got that i can add is this:
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They are both 800mhz, but have different timings. afaik this will work, but it will run at the slowst ram speed(?).

Second question is based on the fact a mate of mine with a very similar setup as mine had problems with 4gb of ram. His PC wouldnt boot at all with 4gb installed(screen would stay black), and only boot a few times with 3gb, then booted fine with 2gb. We tried the 4gb of ram in my PC and i had the same problem & im anticipating having this problem again when i try and put the above ram in.

Anyone have any ideas whats could be causing this problem & a way around it?

thanks guys

[GSte]

Yes, it is as you said, you will need to run it all at the slower timings, but it will work.

If it won't boot with 4 sticks you'll need to increase the Northbridge voltage (vMCH) a notch at a time until it's stable.

[Andeh13]

Im guessing i can find that voltage in the bios? Is it just a matter of trial and error until it is stable?

thanks

[GSte]

Yes, just up it a notch at a time until stable... it will be in the BIOS under 'chipset' something or other, never owned a Gigabyte board so unfamiliar with their BIOS layout sorry..... if it's not stable by about 1.65v you may have some other issue....

[DDY]

Some motherboards have trouble with 4 double sided DIMMs, trouble could mean not posting, poor stability etc.

Here is an example of the P31 chipset having this problem.

Because of chipset limitations, do not populate both DIMM sockets of the same channel (e.g. DDRII1 and DDRII2), or populate 4 DIMM sockets with double-sided memory modules to prevent system's failure to start or incorrect detection of memory modules. Please refer to the user manual for the memory configurations table.

[GSte]

That's surprising to see from a modern chipset.... would be surprised if a P35 board had that issue, but worth noting, well found

[Thorsson]

The first set likes 2.1v, the second 1.9v. I'd try to match a set that also likes 2.1v myself.

[GSte]

The cas4 is verified to operate at the JEDEC standard of 1.8v with 5-5-5-18 timings, so it will be fine with 5-5-5-15 at 1.9v.

[Thorsson]

That's good. But another set of higher spec, 2.1v RAM will almost certainly allow a higher OC @ 1:1, FWIW. Of course if you're not OCing then probably any PC6400 will do.

[TimmiT]

From a software side , you need to be sure your OS can hndle it too. Not sure on XP (because I have low ram on my XP machines), but with Vista, you need to be sure the proper updates are installed to allow for >2gig. When I built the one for the wife, I had to pull 3 sticks to boot up, finish the install, and get the updates. Then all was smooth.

[Thorsson]

We've had the 4Gb debate many times here. Essentially any 32 bit OS will see a maximum of ~ 3.2Gb. A 64 bit OS should see all 4Gb. I can confirm that Vista64 saw all my 4Gb immediately on installation.

Some people have had problems installing their OS with 4Gb, and others can't even boot up. Frequently that is cured by giving the RAM the correct voltage, rather than the mobo default. Never heard of having to boot up/install with one stick on a C2D system though.

[hermeticist]

People do seem to be having problems running 4GB, particularly it seems 4 X 1GB on P35 (I`m sure most `boards claim to support 8GB....!). The problems generally seem to stem from a lack of voltage (requiring an increase to the Northbridge [memory controller] - as GSte mentions). Another side effect of populating all slots seem to be a lower maximum overclock.

[Thorsson]

The lower maximum overclock is probably down to two reasons. Firstly, you can only OC to the speed of the worst stick. Secondly, this NB voltage issue, 4 sticks need more and OC needs more...

Can't say I've had any problem running 4 sticks on the IP35 Pro, although I'm only running at 3.2. I have had the (PC6400) RAM running at over 1000MHz though, with nothing overvolted.