Question about Timing and Manual Adjustment

[Poxal]

I can't seem to be able to adjust my timing manually on my mobo.
Heres the bios section.

If I enable "DDRII Timing Item" the system refuses to post! I am guessing it is because I dont have all the settings right.
When I enable the timing all the cyan colored items become white (with the settings you see), and I only adjust CAS, tRCD, tRP, and tRas, as I dont know what to set the top 8 setting to! Also what about the tRRD? I leave it at 5. I can set it to what it boots now (5-5-5-15 1T) and no post....5-5-5-12 2T...no post.
The command rate setting is adjustable when the manual timing mode is disabled, but no matter what I set that to the system boots at 5-5-5-15 1T.
Let me ask this out of curiosity. Is 5-5-5-12 2T going to be faster than 5-5-5-15 1T? I am to understand that 1T is faster than 2T.
This is the most confusing part to me and would appreciate some input.
Here is my cpu-z.

 

[mpjesse]

1T is faster

 

[Poxal]

1T is faster

Ah thanks! Soo, 5-5-5-15 1T is better. Do you think this is as fast (tight) as the memory will run at its rated 800Mhz? Am I wasting my time trying to manually time it?

 

[Mondoman]

... Do you think this is as fast (tight) as the memory will run at its rated 800Mhz? ...

It would sure help to know the model number of your memory...

 

[Poxal]

... Do you think this is as fast (tight) as the memory will run at its rated 800Mhz? ...

It would sure help to know the model number of your memory...

Ya, I suppose that would help!
CORSAIR XMS2 2GB (2 x 1GB)
TWIN2X2048-6400
Its the C5 version rated to run 5-5-5-12 2T @ 800Mhz

Also...I dont know if this matters, but I will throw this in
The memory is rated to run at 1.9v. I have read that it runs best at this voltage. My mobo will only let me select 1.8v or 2.0v. I have it running at 2.0v because I get a couple memtest errors at 1.8v. The bios shows 1.95v with the 2.0v selected. Runs error free at this voltage.

 

[Mondoman]

...
The memory is rated to run at 1.9v. I have read that it runs best at this voltage...

No, that's just the voltage that the spec speed and latency timings are guaranteed at. This post might help explain things:
http://forumz.tomshardware.com/hardware/modules.php?name=Forums&file=viewtopic&p=1249881#1249881

 

[Dahak]

You are always better to run it slightly higher than lower if that is all the options you get in the bios.My crucial ddr500 is supposed to use 2.8volts,but my bios only gives 2.75 and 2.85.I set it at 2.85.Believe it or not but a lower than recommended voltage will actually hurt your ram more than over voltage.Goodluck.

Dahak

AMD X2-4400+@2.6 S-939
EVGA NF4 SLI MB
2X EVGA 7800GT IN SLI
2X 512MB CRUCIAL BALLISTIX DDR500
WD300GIG HD
EXTREME 19IN.MONITOR 1280X1024
THERMALTAKE TOUGHPOWER 850WATT PSU
COOLERMASTER MINI R120

 

[Mondoman]

..a lower than recommended voltage will actually hurt your ram more than over voltage.

To clarify, the poster is talking about memory *performance*, not about the memory hardware itself, for which overvoltage is worse than undervoltage.

 

[TheProfiler]

Useful info. I was always in dillema about 1T/2T thingy.

 

[Poxal]

Thanks for everyones help thus far. I am still unable to manually set the ram in my bios. I'm not sure why.
I have seen a few people with this memory run it with a Cas of 4. I don't know if this is at 800Mhz or not. Is it normal to be able to run C5 memory at C4? The C5 version takes 1.9v, but the C4 takes 2.1v. I do understand that lowering the speed would allow me to tighten it up, but I have it running at 800Mhz and would like to keep it there.
Enlightened by Mondomans' link above, I want to get more than just 'stock' out of this ram. Any ideas?
Is 5-5-5-15 1T considered a 'overclock' compared to 5-5-5-12 2T?
Does the 1T command rate make up for the drop in tRAS to 15 by a significant amount ?
I dont mean to ask the same questions, I just want *more* out of my memory!