Sempron 64 2800+ overclocking

[imported_goku]

I'm new to the AMD 64 platform and I recently got a Nforce3-a motherboard with a sempron 64 2800+ processor. I'm trying to overclock this thing and it's being fussy. I've currently got it up to 1.8ghz but even this seems to be unstable. I've heard of people getting 250MHZ on this board easily and this processor up to 300 (FSB). I've tried changing the HTT multiplier but not results (This effects the clock speed, correct? So technically reducing the HTT multiplier should reduce Internal clock speed?) Anyways I've currently got it at 230MHZ FSB and it was unstable, so I laxed the timings so that it's now T2, I've also got the ram running in a divider despite being PC4000 memory.. Any ideas? (Can't be PSU cause it's a decent one)

 

[RadonPL]

I've got my 90nm Sempron running at 340MHz HTT x8 at 1.525V with my cheap 1.5GB Hynix D43 RAM at the stock 200MHz speed.

"So technically reducing the HTT multiplier should reduce Internal clock speed?" Reducing the multiplier reduces the Hypertransport speed between the CPU and Northbridge, which on our NF3 should be approximately 800-1000MHz. Mine is 340*3=1020MHz and it is still stable, I love DFI!

My advice is to increase the voltage. An increase from 1.4V (90nm, is your Sempron 130nm?) to 1.525V increased the temperature by 17 degreesC with the 51% overclock using the stock AMD HSF.

"I've also got the ram running in a divider despite being PC4000 memory" There is nothing wrong with using the devider. You have to live with it if you want a high overclock. Mine is approx. 6/10.

Good luck!

 

[imported_goku]

Originally posted by: RadonPL
I've got my 90nm Sempron running at 340MHz HTT x8 at 1.525V with my cheap 1.5GB Hynix D43 RAM at the stock 200MHz speed.

"So technically reducing the HTT multiplier should reduce Internal clock speed?" Reducing the multiplier reduces the Hypertransport speed between the CPU and Northbridge, which on our NF3 should be approximately 800-1000MHz. Mine is 340*3=1020MHz and it is still stable, I love DFI!

My advice is to increase the voltage. An increase from 1.4V (90nm, is your Sempron 130nm?) to 1.525V increased the temperature by 17 degreesC with the 51% overclock using the stock AMD HSF.

"I've also got the ram running in a divider despite being PC4000 memory" There is nothing wrong with using the devider. You have to live with it if you want a high overclock. Mine is approx. 6/10.

Good luck!

There is something wrong with it if the 'fsb' is less than that of the ram's rated speed.

 

[PingSpike]

The A64 doesn't actually have a FSB, so don't worry about that.

Sempron 64 2800+ @ 2.4ghz settings: (this assumes you have the 256k cache model with the 8x multiplier)
Multiplier at 8x
CPU clock at 300 (if your board can do it) this setting is often refered to as FSB.
LDT/HTT multiplier at 2x (sometimes called 400mhz setting) = hypertransport of 600mhz. You can try 3x as well, but I'd do it later.
Memory set at 133mhz setting. CPU/12 = 200mhz speed for ram.

 

[SunnyD]

Originally posted by: PingSpike
The A64 doesn't actually have a FSB, so don't worry about that.

Sempron 64 2800+ @ 2.4ghz settings: (this assumes you have the 256k cache model with the 8x multiplier)
Multiplier at 8x
CPU clock at 300 (if your board can do it) this setting is often refered to as FSB.
LDT/HTT multiplier at 2x (sometimes called 400mhz setting) = hypertransport of 600mhz. You can try 3x as well, but I'd do it later.
Memory set at 133mhz setting. CPU/12 = 200mhz speed for ram.

I'm confused... don't you want the HT bus running at 800MHz as normal? Or am I missing something? (I need a better heatsink before I try any of this, I'm on an Infinity NF4X PCIe board)

 

[furballi]

The ECS NF3 754 may not be able to push this processor beyond 1.8GHz. It's probably the fault of the MB and the 8x multiplier CPU. This board works fine with the Sempron 3100...easy 2.25GHz (250MHz FSB) at 166 RAM speed and 3x HTT. You may need to bump Vcore up to +3.4%.

I put the same 2800 Sempron in the ECS NF4 754 and it ran fine up to 289MHz (2.31GHz) 2.5-3-3-6-1T with 3x HT and 166 memory divider. Vcore is +125mV. Vdimm at stock. Compatible with Corsair VS and Kingston ValueRam.

 

[RadonPL]

Originally posted by: SunnyD

Originally posted by: PingSpike
The A64 doesn't actually have a FSB, so don't worry about that.
LDT/HTT multiplier at 2x (sometimes called 400mhz setting) = hypertransport of 600mhz. You can try 3x as well, but I'd do it later.
Memory set at 133mhz setting. CPU/12 = 200mhz speed for ram.

I'm confused... don't you want the HT bus running at 800MHz as normal?

Benchmark, Benchmark, Benchmark!! How will you know unless you Benchmark?

If the HTT speed is set 600MHz = 1200Mbit/s is hampering your performance too much, then change it to 800MHz = 1600Mbit/s. Imho the increased CPU speed will offset this. Unless you are using SLI with two x16 lanes, I wouldn't worry too much.

The Athlon64 was released in 2003, the A64 does not have a FSB since it connects to the RAM directly. The HTT bus just sends data to the Northbridge.

Like this

 

[PingSpike]

Originally posted by: SunnyD

Originally posted by: PingSpike
The A64 doesn't actually have a FSB, so don't worry about that.

Sempron 64 2800+ @ 2.4ghz settings: (this assumes you have the 256k cache model with the 8x multiplier)
Multiplier at 8x
CPU clock at 300 (if your board can do it) this setting is often refered to as FSB.
LDT/HTT multiplier at 2x (sometimes called 400mhz setting) = hypertransport of 600mhz. You can try 3x as well, but I'd do it later.
Memory set at 133mhz setting. CPU/12 = 200mhz speed for ram.

I'm confused... don't you want the HT bus running at 800MHz as normal? Or am I missing something? (I need a better heatsink before I try any of this, I'm on an Infinity NF4X PCIe board)

The hypertransport bus speed = Cpu clock * HTT multiplier (LDT). Since that bus isn't anywhere near saturated you want to keep it under its rated speed. Although I think a lot of boards can run it higher without problems, it *is* something that can cause stability problems.

You can always try pushing it up after you get the thing booted into windows and run it through prime for a bit.

 

[Zap]

If it was a Fry's combo, then you got a Palermo D0 core. Those are the early 90nm chips and may need voltage (though still cool running) to clock high. The other thing is that some NF3 boards are finicky with overclocking Palermo core chips. furballi mentioned that he had issues with overclocking his Palermo on the ECS NF3 board. I've had similar issues with overclocking one (a 2600+ D0) on a Chaintech VNF3-250 where I just couldn't get high clocks, but that chip tears it up on a Biostar Tforce, and not quite as good but does a decent overclock on an Epox 8KNDA3I (or whatever that part number was).

Here are the settings that should clock you up to the HTT/FSB limit if your setup will do it...

Set RAM to 166, set latencies to what your RAM is rated for (likely CAS 3). Set HT multiplier to 3X. Bump vcore a notch or two, then take HTT to 250.

The other thing is are you using SATA? I think people may be getting better clocks using EIDE on this particular board - furballi please correct me if you think I'm wrong.

 

[imported_goku]

Nevermind guys, my initial speculations were correct (on what HTT is and overclocking ability). Turns out it was a simple issue, I currently have the computer running at HTT 2X (1ghz) since I haven't tried 3x yet at the 'FSB' speed of 250mhz (was limited to 230 before). At this moment I believe my issue was I simply wasn't getting enough juice into the processor (had it on the 1% setting?) so it's on the 5% setting now. Will report back on my most aggressive setttings. I asked the stupid questions cause things weren't what they seemed.

 

[imported_goku]

Great, I just realized something.. I have a feeling this memory controller doesn't support 250mhz sync with memory.. Because, the only time the system will boot is when I select 'limit memory clocks to 166mhz'. I've tried setting to T2, increasing memory voltage, laxing memory timings, nothing will work.. So at the moment I have my PC4000 memory running at 166mhz, T1, 2.5-3-3-6, and HT at 3X which is effectively 1500mhz HTT..... Does the integrated memory controller not support synced speeds past 230mhz?

 

[Zap]

Have you tried raising memory voltage? Often PC4000 memory is "rated" at that speed only at higher voltages.

 

[imported_goku]

Originally posted by: Zap
Have you tried raising memory voltage? Often PC4000 memory is "rated" at that speed only at higher voltages.

It's rated at 2.8v and I raised it to 2.9 just in case.. (Didn't you read the post above you?)

 

[furballi]

I'd give Zap's settings a try. I suggests that you swap the 2800 with the 3100 if you want to overclock with the ECS NF3 board. This board is not very happy with an 8x CPU (2600 and 2800 Semprons).