WPCREDIT tweaks for the A64

[CodeRed]

Gents,

I've just found a way to really boost your A64 performance using WPCREDIT.

The A64 mem controller registers can be accessed using WPCREDIT using Bus #0, Device #24, Function #2. There are 4 main registers that I have been playing with:

0x88 DRAM Timing Low
0x8C DRAM Timing High
0x90 DRAM Configuration Low
0x94 DRAM Configuration High

The timings registers set all the DRAM timings params (as you'd expect), but there are many more than most BIOSes will show you. The best performance is obtained using:

Column Address Strobe # (CAS) = 2.0
Row Cycle Time (Trc) = 8
Row Refresh Cycle Time (Trfc) = 12
RAS# to CAS# delay (Trcd) = 2
Row to Row delay (Trrd) = 2
Min RAS Active Time (Tras) = 5
Row Precharge Time (Trp) = 2
Write Recovery Time (Twr) = 2
Write to Read Delay (Twtr) = 1
Read to Write Delay (Trtw) = 1

I normally write this as 2-8-12-2-2-5-2-2-1-1 for convenience ... not that rememering all those values is easy.

To set the mem timings to the above values change the registers as follows:
reg 0x88 to 0x02522311
reg 0x8C to 0x00000B00
(use 32 bit mode in WPCREDIT)

I have only begun to experiment with the Config registers but some of the things I have tried are setting the Asynchronous Latency Value (controlled by reg 0x94). Normally my BIOS sets this to 7ns, but when I dropped it to 4ns there was a healthy boost to my memory performance. To do this set bits 0-3 of reg 0x94 to 0100 (binary) (4 for those who cant read binary).

Just to make things more interesting, bits 22-20 of reg 0x94 control the DRAM speed (200, 166, 133, 100 Mhz). There are several reserved values, and I decided to try 110. Surprisingly this gave me a mem speed somewhere inbetween 200 and 166 MHz. This may be a 183 Mhz mem option I need to test some more to confirm these results.

Oh, 2T is also easy to disable

We no longer have to worry about BIOS updates, its all there in the DRAM registers. Over time I may write a simple windows app to set all this up in a user friendly fashion ... just need to find the time.

Only thing I cant do is set the bank interleave. Doing so would reorder the physical memory locations ... not something I think windoze would be happy with

Try it and compare your before and after benchies with something like pifast or superpi and you'll see the boost.

============================================

V0.31 of A64 tweaker is now ready (win 64 bit compatible now)
jump to this post
http://www.xtremesystems.org/forums/...345#post505345

or just download :a64tweaker_V031.zip * linked fixed now *

heres another dl link for those who have problems downloading the app: v0.50 XT beta or v0.31 final

v0.60 Beta is up!

_

[Kunaak]

Excellent Finds there

[LORD]

Nice find. Did you discover all these your self?

[Ragnarok]

of course he did , he's worth his salt

[CodeRed]

Originally posted by LORD
Nice find. Did you discover all these your self?

I woudlnt call it discover ... just read the write AMD tech docs.
This info has been right under our noses since day 1 of the A64 release.


For those who want to disable 2T and dont have the option in the BIOs, just set bit 28 of register 0x90 to 0.


looks like there may also be ways to improve the memory overclocks, not just the aggressiveness of the settings ... I'll get back on this one.

[blinky]

Awesome find bro!!!!!!!

:thumbsup:

[HKPolice]

I get about 30MB/s faster in Sandra, not bad, but every bit helps I guess

[CodeRed]

Originally posted by HKPolice
I get about 30MB/s faster in Sandra, not bad, but every bit helps I guess

Sandra doesnt really reflect the gains .. try SuperPi, Pifast or check your 3dmark01 lobby scores

[pik-ard v1.1]

sticky? something like this deserves it, or atleast to be combined in some a64 guide.

[Mariachi]

Sticky

[HKPolice]

I can only change these settings while running CPU/12, freezes while in 1:1, and the 183Mhz as well as the 4ns settings freeze as well... I guess I'm already at the limit of my chips/mobo

[CodeRed]

Originally posted by HKPolice
I can only change these settings while running CPU/12, freezes while in 1:1, and the 183Mhz as well as the 4ns settings freeze as well... I guess I'm already at the limit of my chips/mobo

Only set the DRAM timings registers then, 0x88 and 0x8C. The 4ns setting is bloody hard on your RAM. Above 250 MHz I have to use 6ns and thats with some fast BH5 at 3.6V.

[HKPolice]

Originally posted by CodeRed
Only set the DRAM timings registers then, 0x88 and 0x8C. The 4ns setting is bloody hard on your RAM. Above 250 MHz I have to use 6ns and thats with some fast BH5 at 3.6V.

Yes, I tried adjusting the timings @ 1:1 but no go.... only works when running with slow ram. Probably just the mobo or maybe the mem controller in the CPU.

What board are u testing it on

[CodeRed]

Mines an AN50R

what mobo u running?


Just a note:
Some of the 'better' boards (eg K8N Pro with the right BIOS) allow you to change most of the timing values rom the BIOS. The only thing they dont (may not) change is the max latency and read preamble values. People with these boards dont need to change registers 0x88 and 0x8C. Just play around with register 0x94.


Another note:
read the "BIOS and Kernel Developers Guide For the Athlon 64" from .AMD. Its a damn good read and sheds the light on a lot of settings, not just for the memory controller. There may be a whole host of other tweaks that are possible ... just gotta start looking and testing.

[macci]

Its funny how I got the 0x94 ram divider tweak to work only once (on GA-K8N F4, 166mode from BIOS)!? Now it just reboots or gives bluescreen.

When it worked Sandra unbuffered went from 1620MB/s to 1725MB/s after I set the 20-22 bits from 101 to 110
So it seems that this setting indeed adjusts the RAM divider.
101 = 1620MB/s = 2310/14 = 165MHz
110 = 1725MB/s = 2310/13 = 178MHz
111 = 2050MB/s = 2310/11 = 210MHz

[CodeRed]

Originally posted by macci
Its funny how I got the 0x94 ram divider tweak to work only once (on GA-K8N F4, 166mode from BIOS)!? Now it just reboots or gives bluescreen.

When it worked Sandra unbuffered went from 1620MB/s to 1725MB/s after I set the 20-22 bits from 101 to 110
So it seems that this setting indeed adjusts the RAM divider.
101 = 1620MB/s = 2310/14 = 165MHz
110 = 1725MB/s = 2310/13 = 178MHz
111 = 2050MB/s = 2310/11 = 210MHz

works every time on my board. I cant really see the usefullness of it ... unless your stuck between some odd HTT limit, CPU limit and mem limit.

Shame it doesnt enable those 0.5x multis

[bias_hjorth]

uhh crasy nice.. glad someone toke their time to do the effort! very nice find codered

[r3b0rN]

nice job

[Jeff]

Great work!

[Shroomalistic]

Originally posted by CodeRed
works every time on my board. I cant really see the usefullness of it ... unless your stuck between some odd HTT limit, CPU limit and mem limit.

Shame it doesnt enable those 0.5x multis

Have you tried crystal cpuid, it works great with the .5 multies for me.

[Shroomalistic]

can one of you guys post a pic of your wpcredit, I cant seem to find what or where to change this value.

EDIT: never mind, I figured it out. I had to change the device, never really used wpcredit before. so far its getting me stable at 230x10 but im not sure what the mem is at now. before I used to have to run it at a 166 to go to 230. I set what I think the mem divider is to 110 in wpcredit 0x94. So iguess thats the 183 divider or whatever.

Thanks for the tips guys

Shroomy

[Boogotop]

really good find here Codered!!!

[cowpuppy]

Ok I've tried getting through this but I'm just not understanding how to work wpcredit. I get the devices set up using Bus #0, Device #24, Function #2. and 32 bit but I get lost after this not being able to find the registers reg 0x88 and the others. If someone would help me out with a rundown of what I'm doing wrong and a screenie would be great.

[Shroomalistic]

ill try to help

heres a little walk through, I just had to figure it out my self too.
this is how I change my ram divider from 166 to 180 or something close to 180.

Start wpcredit
go to the edit tab and select device or press (ctrl+d)

scroll down to pci bus : 0, device : 24, function :2 and double click on it.

go to the veiw tab and select bit mod or 32 bits

now look at the data it shows you, you will see the 90 on the left and the 00000004 on the top, that will equal 0x94 in the settings.
click on the value where they meet and double click on it.

on the bottom you will see a hex and a bin value. Each number in the bin value is a different bit. so in this case I was trying to change the bit 22-20 settings from 101 to 110. (22=1,21=0,20=1) so I change the 21 value to 1 from 0 and the 20 value from 0 to 1.

Dont forget to hit set when your done.

I hope this helps, I will look for the setting you are trying to change and post a couple of pics for ya.

[Shroomalistic]

Well for me, it does change the ram divider but it changes to a 200 not a 180. Not sure if there really is a 180 in there or not.

EDIT: scratch that last coment, it does seem to be working. I was just able to bench at 240x10 with 22-20 set to 110.