Started out wrong, but reformatted/reinstalled everything, redid all my tweaks, restored vid card settings, and...
Nothing. No real improvement in FS9 performance. The upgrade was from an AMD 2000 Athlon (1.2GHz) to a Sempron 2800 (2.0GHz), but using wcpuid/cpuclk shows an Athlon running at just over 1.2GHz. ???
Either I've done something wrong, or I've been ripped off. Any thoughts?  ???

Hm. Forgot about 3D Mark; I'll try that. But if it yields the same result, what does that mean? Does the mobo still think it has the old CPU installed, and if so, why?

You haven't got your bios set up properly Rottydaddy.

It's not hard if you know what your doing  

You'll find that your BIOS has either reset itself to safe defaults or is still running at the old bus speed set for the old CPU.

I'm amazed you actually got it to work at all with such limited knowledge, and you may even find that your mainboard does not support that CPU which is meant to run on a 166mhz (333mhz DDR) front side bus speed.

A sempron 2800 socket A CPU runs with a locked 12x cpu multiplier and a 166mhz FSB speed giving 1992mhz, almost 2.0ghz.........  (12 x 166mhz = 1992mhz)

Your FSB speed is set to 100mhz, (probably a safe default setting your bios has been set or reverted to).

I know that because your current speed is 1.2ghz (12 x 100 mhz ! )

If your mainboard supports 166mhz FSB speed, you can change it to that and you will have your 2800+ as intended, if your mainboard doesn't support the 166mhz speed, then it won't work. You weren't ripped off, unless the seller mislead you into believing the cpu would work properly on your system.

IF your mainboard doesn't support the 166mhz FSB, you need to get one that does. Make sure you buy a fully featured "nForce2 ultra 400" chipset based mainboard if you change the mainboard, they are reasonably cheap.

If your mainboard supports 200mhz FSB speed (as nForce2 ultra 400 chipsets  do), then you could, (with care, cooling and a bit of research), up the FSB to 200mhz and with luck, turn your Humble Sempron into a killer overclocker with a new speed of 12 x 200mhz = 2.4ghz or (roughly) a 3200+ !

It's in the bios, or if as you say, it does actually support it, it may need a bios upgrade, but that's a last option.

Try to find hidden bios menus that provide the setting, get back to me here and state your exact mobo ID, and I can find out how for you.

Thanx again. I've gotta get going, but i took a minute to check BIOS again, and found that the DRAM timing was set for manual, with CAS latency on 3, bank interleave disabled, Trp at 5t, Tras non-DDR at 7t, and Active to CMD at 5T. Set the Timing to "by SPD" but other values didn't change, even after reboot.
I'll have another crack at it later, and if you're still curious, here's the mobo specs:
Epox EP8KRAI
Northbridge: KT600
Southbridge: VT8237

According to Epox, this board will support FSB speeds of 333MHz with my setup; I have just shy of 1GB of compatible RAM  (PC2700). The board alledgedly will do up to 400 MHz with just two sticks (unstable with three); for now I have three, but 333 would be better than 266, which is what I'm getting.
I'd figured setting DRAM Timing to "by SPD" would auto-detect the RAM and allow for the max. that the CPU could handle... maybe I need to go manual with different settings than those listed?

Did you ever clear the CMOS after installing the new CPU? That's a must do as it allows the BIOS to detect the new CPU settings.

Also, some BIOS will start out at minimum safe defaults. That may be what happened here -- you're at 100 FSB. You can change that in the "Power BIOS Features" section in the BIOS setup. You'll be able to adjust the CPU frequency 166 (or higher if you want to overclock it.)

If you don't have the latest BIOS (8/10/2004), it may be required for Sempron compatibility. http://www.epox.com/USA/article.asp?ID=1779

You're manual will give you details on how to do any of this. http://www.epox.com/USA/article.asp?ID=1855
(The download is really slow.)

The setting is called "CPU Clock" which is the front side bus setting, enter "166" in there. Turn off "full screen logo" if that's enabled so you can see what's happening at bootup.

"System Performance" and "CPU Timing" can also be played with (increased) to allow faster timings if your hardware will handle it.

The "Expert" setting sometimes allows more tweaking options..

Be careful and be prepared to make the CMOS reset jumper your friend.    8)

The AMD Sempron CPU's are a fairly serious processor and are essentially a Barton (thoroughbred "b" core?) with half the L2 cache disabled. (Total 256k L2 Cache, Barton's have 512k). The absence of the extra L2 cache RAM onboard the CPU has little effect on overall performance of these AMD cpu's. They are pretty good value.

Your RAM's Performance Rating (PC number..... ie PC2700) will determine it's upper speed limit, and pushing the RAM beyond that speed is getting into serious overclocking territory and not recommended (not in this forum anyway).

PC2100 = 133mhz,   PC2700 = 166mhz,  PC3200 = 200mhz     ( x2 gives DDR rating, so PC3200 is 400mhz DDR)

If, say, you wanted to run the CPU/FSB at 200mhz, (overclocked from the cpu's default of 166mhz), you would need to run PC3200 RAM modules if you want the memory bus to run in "sync" with the CPU/FSB speed of 200mhz.

I didn't see any option to seperate the FSB Speed from the memory speed (called a divider) in your BIOS manual, which is odd considering the other options you have available. Maybe it's there somewhere, but Like I said earlier, it's probably faster to run the PC bus speeds in "Sync".  (ie. ... CPU/FSB/MEM all at 166mhz).

Clearing CMOS is not a good idea if you don't know how to set up ALL of your bios options properly, and  should be used by the novice only in emergencies where the system will not boot. This is because it usually sets "Safe" default settings, and will slow the system down considerably.

There is usually only one particular set of parameters that matches the hardware perfectly as far as performance versus stability is concerned, and you will need to benchmark the FSB and CPU bandwidth seperately to verify the best settings.

It's best to start with the hardware's defaults. If you want more advanced help, you might want to post a new thread in the overclocking forum, though some of the above covers the principles.

Never have used Epox boards, but there could be a bus speed jumper somewhere on the board... as it seems to run the same speed as the old one

If that doesn't help, get a BIOS update


SPD is the 3mmx3mm thing on memory modules, usually located near the connectors. It's used for configuration (and for lockout tricks as compaq did for a while)