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Running Samsung TCCD at DDR600+ on DFI nForce4

Memory by kakaroto @ 2005-03-25

Getting your brand new A64 S939 to overclock to high DDR600 speeds is not an easy feat. Even with high quality memory you still need a lot of tweaks to get everything running stable. In this guide we show how to reach stability at DDR600 speeds on the nForce4 board from DFI.

Test Setup & PC4400 1GB LE

Test Setup

I used a competitively priced A64 Winchester CPU in test setup, rather then an overly expensive A64 FX-?? one.

Athlon 64 3000+ (CBBHD 0448 RPMW)

DFI nF4 Ultra-D rev. A02

G.skill PC4400 & 4800 LE/LA

Tagan 480Watt-U22

I had quite a bit of luck with the on-die memory controller of the A64 3000+ as it turned it runs at DDR600 speeds flawlessly.

Cooling: I can’t stress this enough; use an 80mm fan or bigger to cool down your memory as it has a very large impact on the result. At lower speeds and voltage the TCCD chips hardly get hot, but when pushing the envelope they start cooking and this will deter the overclocking potential.

G.Skill PC4400 1GB LE

This memory comes with Samsung TCCD 431 chips. Theoretically newer revision TCCD are better so they more likely to overclock better. Although I have older one, they seem to be performing very well.

Madshrimps (c)

2x 512MB DDR550 2.5-3-3-6 1T Dual Channel (10 pass Memtest86+)

BIOS Settings

Vddr: 2.7v
Tcl: 2.5
Trcd: 3
Tras: 6
Trp: 3
Trc: 9
Trfc: 12
Trrd: 2
Twr: 2
Twrt: 2
Trwt: 2
Tref: 4708 (166MHz 1.95us)
Twcl: 1

Bank int.: Enable
Skew control: 255 +
Drive strength: 7
Data strength: 4
Max. Async: 7ns
Read Preamble: 5ns
Idle Cycle: AUTO
Dyn. Counter: Enable
R/W Bypass: 16x
Bypass Max: 7x
32Bit Gran.: Disable

With these settings I got high performance and stability. The Tref (Refresh interval) can set to 3072 (200MHz 3.9us) for even better performance.

If the settings mentioned above prove not to be stable, you can change the following:

- Max. Async. to 8ns
- Lower the refresh interval (Tref)
- Trrd to 3
- Idle Cycle at 128/256

These settings will increase stability and keep the performance at a descent level. If those settings are still unstable, there is something wrong with your memory or memory controller. You make sure your memory is not the issue; test the memory modules separately in bank 1 or 2.

When the memory works fine, then the problem must be the memory controller. You should disable the Command per Clock (CPC). If the problem is still there, you should consider lowering the speeds or, as a last resort, buy another processor.

2x 512MB DDR600 2.5-3-3-6 1T Dual Channel (15 pass Memtest86+)

BIOS Settings

Vddr: 2.7v
Tcl: 2.5
Trcd: 3
Tras: 6
Trp: 3
Trc: 12
Trfc: 14
Trrd: 2
Twr: 2
Twrt: 2
Trwt: 2
Tref: 4708 (166MHz 1.95us)
Twcl: 1

Bank int.: Enable
Skew control: 255 +
Drive strength: 7
Data strength: 4
Max. Async: 8ns
Read Preamble: 5ns
Idle Cycle: AUTO
Dyn. Counter: Enable
R/W Bypass: 16x
Bypass Max: 7x
32Bit Gran.: Disable

Again these settings are for high performance and stability. The Tref (Refresh interval) can set to 3072 (200MHz 3.9us) for better performance.

When those settings are not stable, you can change the following:

- Max. Async. to 8ns
- Lower the refresh interval (Tref)
- Trrd to 3
- Twr to 3
- Trwt to 3
- Idle Cycle at 128/256

If those settings are still unstable, be careful working with a higher voltage. TCCD does not like high voltage compare to Winbond BH5. Maybe the newer revision TCCD like higher voltage but this one doesn’t. Always start with a lower voltage and increase the voltage step by step to a satisfied value. As you see I only used 2.7v. higher voltage 2.8 ~ 2.9v only gives me errors in Memtest86+!

Always try to run at CL2.5-3-3-6 1T to keep the performance at a high level. But if there is no other way to get this stable you can raise the Trcd to 4. This will decrease the bandwidth by 100-150Mb.

Test known-how’s

- Drive strength 7 is the best value for stability, I recommend not increasing or decreasing it.

- Always set the bank interleave to enable when you are using two modules. This will increase the performance and stability.

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