Overclocked 4800+/A8N32-SLI - what else can I do?

[Brisos]

Hi,

I would like to list the steps I took to OC my machine so that someone more knowledgeable than me can tell me what I could do to improve the OC. I apologize in advance for the long post, and am grateful for you reading it!

Here is my rig:

AMD 4800+ (Socket 939) (2.4GHZ base)
Asus A8N32 SLI Deluxe Mobo (using latest non-beta bios - 1303)
4x1GB DDR PC3200 (Kingston)
7800GTX 512MB (XFX)
650W Antec PSU
Sound Blaster Audigy 2 ZS

I have had this machine for about 2-3 years and decided to buy a new video card (9800GTX). Before the video card is delivered I figured I could try to OC my CPU, fearing it might be dragging my new Video card down.

I had never done any OC before, only seen it done once on an Intel Core 2 Duo a few months ago. I read everything I could find. Guides, Forums, manuals and I think I got a good hand on things.

I did all the OC from the bios, since Clockgen does not seem to be working with my Mobo.

Here are the steps I took:

1)Flashed Bios from 1009 to 1303
2)Installed Prime, CPUz, Clockgen (just to see the clocks), and Core Temp
3)Checked default settings with CPUz:
CPU Multi 12x
FSB 200 (total 2.4GHZ)
RAM 200MHZ
Vcore around 1.4V
Core Temp 40C (idle) 45C (stressed)
Watercooling on CPU

4)Changed settings in BIOS:
-Upped FSB to 250 (by +5 steps)
-Lowered Memclock to 166MHZ
-Lowered LDT to 3x
-Set PCI Express to 100Mhz andthe SB/NB to 200MHz and x5
-Left Vcore and CPU set to AUTO

What I noticed by leaving the Vcore and CPU set to AUTO was that at a FSB of 225MHZ all was going as expected. At 230MHZ the CPU Multi was automatically lowered to 11x (down from 12x). And at 250MHZ the CPU Multi was lowered to 10x.

Thus making my best OC at 245MHZ with a CPU Multi of 12x 225MHZ = 2700MHZ (also atteined with 245MHZ x11 = 2695HZ).

This is a fair 300MHZ boost, but is nothing close to what people have been reporting for this Motherboard. The highest reports I have seen went over 3000MHZ, and Averages are in the 2800+ MHZ range.

I then tried to go back and manually set the CPU Multi to 12x to see if I could go past 225MHZ. At 225MHZ everything is fine, stable under Prime and Super PI on the heavy stress tests. At 229MHZ as well. But at 230MHZ, I can't even get Windows to Boot. The machien will try booting XP and reboot on its own or the BIOS wil lreturn an "Overclocking failed" error.

-I tried increasing the CPU Vcore incrementally to no avail. The CPU runs fine even on the max Vcore setting (1.575V) at Core Temps of 45-50V under load. At all of these settings the CPU Core Temps never budged much (53C max).

-Ram clock is set at 166MHZ and is way lower than the 200MHZ default. I do not think the RAM is the limiting factor at this FSB setting.

-I still tried to lower the RAM to 133MHZ, but it will not work. Even at default settings (all bios set to default) the PC will not boot with RAM set to 133MHZ. It has to either be 166 or 200.

-I tried playing with the RAM voltage with no success.

Am I missing something? Did I reach the maxium OC for my rig? Is there anything else I could try?

 

[myocardia]

Originally posted by: Brisos
Am I missing something?

Yes, your motherboard has more than one setting for lowering your HT multiplier, and you've only lowered one of them. Lower your SB/NB frequency to 4x. Leave the bandwidth (what Asus calls LinkWidth) at 16X bidirectional, though. Also, you'll want to raise your memory timings to 3-4-4-8, until you find out how fast your CPU will run.

edit: And definitely manually lock your CPU multiplier @ 12x.

 

[Martimus]

At 250MHz, the ram should be running at DDR415 (Or approximately so, AMD does a straight divider at the processor speed, and I don't know what the divider for that processor is for 166MHz) so it is slightly overclocked. Also here is a link that could help you: http://forums.anandtech.com/me...id=28&threadid=1497607 ; it is the old A64 overclocking sticky.

edit: I agree with Myocardia; lowering the NB/SB multiplier to 4x will probably get you through that 230MHz wall.

 

[Brisos]

Dang! I researched those K8/Sb/NB values all over the place when I was trying to figure out where my HTT/LDT settings were in the Asus bios. One of the guides I read explained that the NB/SB multiplier should be left a 5x, that it was not used for the CPU but for the SLI... you know what I don't even remember. I will give this a shot.

Should I set the NB/SB at 4x even if I set the other multi at 3x? Or should I keep both at the same level?

I realize 4x is good enough as long as I do not go over 250MHZ on the FSB, but I thought I'd ask anyway.

2 more questions:

1)Should I leave the SB/NB frequency set to 200MHZ? Or is that something I need to tweak as well?

2)Could you give me a bit more details on the memory timing changes? I know how to change them, but read nowhere that this was useful for OCing the CPU. I would like to understand what it will do, even if you can jsut throw the basic explanation my way.

Thanks again for the tips!

 

[Brisos]

Ok - I tried it. The NB/SB multi set to 4x did not help. Still stuck at 225 x12. I tried changing the Memory timings as well, no improvements

 

[lopri]

How far do you expect your CPU to clock? Socket 939 X2 4800+ will top around 2.7~2.8GHz.

 

[kman79]

I have the processor but with an A8N-SLI Premium. Max i got out of it was 2.8Ghz

Just like you, I'm considering upgrading to 9800GTX from my current 7800GTX, could you share your thoughts on the upgrade? In your opinion, is the 4800 still a capable processor when partnered with a 9800GTX to run the newest games? Any input on this is greatly appreciated

 

[myocardia]

kman, with your processor, anything faster than an 8800GT will be "wasted", as long as you still have the 2001FP. Of course, it wouldn't hurt to have a faster video card, since you'd be able to take advantage of it, when you upgrade the rest of your system.

 

[Ratman6161]

This AT article is pretty much everything you need to know about socket 939 overclocking.