Need OC help with OCZ Platinum

[palouse]

Why can't I get my RAM to OC beyond the 2:1 divider?

My RAM will only work with the 2:1 ratio. Stock timings are 2.5-3-2-5, and advertised timings 2-3-2-5.

I can not get the system to boot into WinXP with any of the tight (stock) timings and a divider smaller than 2:1. The MB has only 3 RAM ratios below "1:1" - 1.2:1. 1.5:1. & 2:1.

I prefer not to go into a "loosen timings" test cycle. I'd like CPU to remain at 2712, and RAM to run at a higher speed (1808MHz or 2260,) on one of the faster ratios, and stock timings.

CURRENT:
- CPU running at 2712MHz, 48 degrees C under Prime95 load.
- 300FSB was highest I felt comfortable for OC.
- RAM 2-2-2-5 1T.
(Since 2.5-3-2-5 settings will not boot with 1.5:1 divider, boots only with 2:1 divider, why not try running 2-2-2-5 2:1? It worked.)
- 8 hours Memtest86+ stable, 12 hours Prime95 stable.
- HTT 3x, CPU multi 9x.
- Looking for 3D gaming performance.
- MB BIOS will not allow a RAM-only OC for test purposes.
- I tried setting commands to "2T", DIMM voltage 2.60 to 2.75, no difference.

2x1024 OCZ Platinum RAM
Venice 3000+ (stock HSF)
ASUS A8N5X w/ latest ASUS BIOS
Sapphire X1800XT-256
1x HD, 1x CDROM, Antec slk3000b case, Antec SP-500w PS.

 

[palouse]

Let me try this again.

 

[Madwand1]

<- stumped.

1.5:1 should work...

If it's any consolation, I've had even worse problems with some specific OCZ RAM -- any OC whatsoever on the CPU, with no OC on the RAM and even underclocking, 2T, C3, etc., causes Memtest errors. Works fine with different RAM.

Try 1 / different sticks to see whether or not it's RAM specific?

Try different CPU clocks to see if you get a threshold of working vs. not working?

Live with the ~3% overall performance loss from 2:1 vs. 1.5:1 considering the CPU gains?

Edit:

nealh suggests a vcore boost (for the on-die mem controller) in the following thread: (assuming it's in the safe zone)

http://forums.anandtech.com/messageview...atid=28&threadid=1841376&enterthread=y

 

[palouse]

Thanks for the reply, and the nealh reference.

Trying 1 stick at a time, or trying the Platinum in my Ultra-D are all options. The Ultra-D would allow me to OC the RAM, one or both sticks, with CPU at a 5x or 6x multi. I would like to know if both sticks OC the same. Nine months ago, I had two variants of OCX Gold, in pairs, where an individual DIMM did not OC the same as its mate. Or, the Ultra-D's CorsairVS could be tested on the A8N5X. That's a lot of testing to find what is likely to be 3 to 4% difference, at ideal. If I could get 5 to 8% or so by going to 1.2:1 on the board, then it might be worth it.

I am using the freeware 3DMark05 "CPU" bmark portion as a measure of performance. I don't even know if that is a valid test.

I don't think it is the RAM. I think it is something I am missing in the BIOS config. I have the CPU set at 1.525 volts, and it shows in CPUZ as 1.55 v. I have changed vDIMM from 2.6 to 2.75. From Zebo's "939 Memory" article, I doubt loosening the timings to go faster would produce better results.

As a data point, I did "throw the system together" when I first started, and tried an initial OC of FSB275 on the CPU, and got ~225 OC on the RAM using the 1.2:1/"333" setting in BIOS. 7 hours Prime95 stable.

The system currently runs cool and stable, so I should probably just leave it. But it's gonna' bug me...

 

[palouse]

I take it all back. I now think it might be a BIOS problem.

I did some testing. The system will not boot at the 1.5:1 (266MHz) divider when the CPU is OC'd beyond 249FSB. I changed timings with no effect, and tried, 2.5-3-2-5, 2.5-337, 3337, 3338, 4448, and 444-10. Each of the above with 1T and 2T command rates.

I can boot with the 1.2 (333MHz) divider all the way to 295FSB, 2.5-3-2-5 2T, less than 5 hours Prime stable. It will not boot at 300FSB.

This BIOS has a few new features that are not in the latest manual, including options to control memory loads for 4Gb and greater, and the equivalent of a CPU lock, with "Auto", "CPU", and "33.33MHz" options. I have tried Auto and 33.33MHz.

I have slowly "disabled" functions, trying to see an impact. I removed the CDRom, Legacy USB support (2.0 remains), 4 Gb support, and others. No change. I don't have C&Q enabled, Plug&Play "Y", HTT 3x, Resources "Auto", etc. Only divider and FSB have an impact on boot to XP. (Well, actually, it won't boot with timings set to 222-5 for the 333MHz divider.)

Does booting at 2:1 or 1.2:1, and NOT booting at 1.5:1 mean that there might be BIOS problems, or should I keep looking? I can't find much on the A8N5X bios on the web.

Could it be an nVidia IDE driver issue? I have seen reference to swapping IDE drivers from nVidia to generic in post on other sites. Given that it will not even get to the Windows Boot Logo?

Thank you for your support.

2x1024 OCZ Platinum RAM, usually 2.5-3-2-5 timing.
Venice 3000+ (stock HSF)
ASUS A8N5X w/ latest ASUS BIOS (3-20-2006)
WindowsXP Home Edition, all patches installed.
Sapphire X1800XT-256
1x HD, 1x CDROM, Antec slk3000b case, Antec SP-500w PS