GA-P35-DS3R won't work with 2*2GB + 2*1GB

[dreamlayers]

I have a GA-P35-DS3R rev 1.0 motherboard with BIOS F13, a Q6600 CPU and EVGA Nvidia 8600GT graphics. Up to now, I've been using 2*1GB DDR2-800 CL5 OCZ Gold XTC OCZ2G8002GK without any problems, passing Memtest and Prime95. I just got 2*2GB OCZ Platinum XTC OCZ2P8004GK. By itself, the 2*2GB also works fine, passing Memtest and Prime95. Either kit can work perfectly at 5-5-5-15 and 1.9V. However, with both, I can at best get a lockup at the graphical BIOS screen. Usually, I got two on-off cycles and then a lockup with no video.

I can boot with 2*2GB + 1GB. Memtest has so far not found any problems, though the transfer rate is lower than 2*2GB. I can also boot with the 2*1GB in the 2 slots closest to the CPU and 2*2GB in the 2 slots further away, but in that case Memtest fails sequential addresses starting at 4096M. This configuration is wrong for dual channel, but I guess it nevertheless ought to work with reduced performance. All the slots seem fine by themselves.

I've tried going to DDR2-533 and relaxing almost all timings, and nothing helped. CL6 can't be used because the 1GB sticks don't work with it. I don't understannd "Static tRead Phase Adjust", so I didn't try changing that, and I didn't try changing each setting by itself. Some people say  'Refresh to ACT delay' can be an issue with 2GB or 4 sticks, and it's suspiciously low on the 2GB sticks, but even increasing it to 80 didn't help. Increasing DDR or MCH voltages doesn't help either. Some say the OCZ Platinum RAM needs 2.1V, but no voltage is listed on the label and by itself the kit is stable at the default voltage. The Gold kit is also stable at 2.1V.

I don't know what to try anymore.

[dmdilks]

The timing & volts are different between the two sets of memory

OCZ2P8004GK - 5-4-4-15 Volts - 2.1V

OCZ2G8002GK - 5-5-5-15 - Volts - 1.8V

[dreamlayers]

By themselves, each set is stable at DDR2-800 5-5-5-15 at both the default voltage and at 2.1V. So, why shouldn't they work together?

Motherboard sensors report the default voltage as 1.89V. There doesn't seem to be a way to set exactly 1.8V, but the OCZ2G8002GK has been working fine with that for years.

[dreamlayers]

If I only put the two OCZ2G8002GK Gold XTC 1GB sticks in the same channel, that works properly. If instead only put two OCZ2P8004GK Platinum XTC 2GB sticks in the same channel, I can't post, just like with all 4 sticks. I've tried both channels, the one closer to the CPU and the one farther away.

I realize that the proper way to install a dual channel kit is to put one stick in each channel, for example in the pair of red or the pair of yellow slots.  I am instead putting the sticks in the closely spaced pairs of slots, one stick in the yellow slot and one in the red slot. This doesn't allow dual channel operation, but it should still work, right? Why does it work with the 1GB sticks but not the 2GB sticks? Does this mean that the 2GB sticks are broken or incompatible with my motherboard?

[dmdilks]

What I'm saying is that they all have to be the same timings and volts to work together. You have tow different volts memory.

The board doesn't know which to boot too when you have all of them in at the same time. Yes by what you are saying is when you have you have two sticks in and just add one of the other stick it works.

Yes the board might boot and the two stick over ride the one stick. But when you have all four sticks than they can't over each other.

[dreamlayers]

I can set the timings and voltages manually, so there's no need to worry about the board selecting sensible timings. Also, if I just put in two sticks from one of the kits, then they are supposed to be matched. I'm just wondering whether having two sticks in one channel and nothing in the other channel should work properly.

Considering that, in the same channel, with nothing in the other channel:

• 2GB + 2GB fails
• 1GB + 1GB works
• one of the 2GB sticks + either 1GB stick works
• the other 2GB stick won't work with either 1GB stick

It sure seems like that other 2GB stick is broken in such a way that it works perfectly by itself in a channel but cannot work with another stick.