Confused over Sempron overclock

[Deanodarlo]

Hi Guys, I'm new to socket 754/939 overclocking after only owning Skt A chips.

I managed to get a sempron 64 1.6ghz for free so thought I'd buld a cheap system out of it. Bought a cheap ASUS motherboard (K8V-MX with via chipset) and set everything up.

Now I know that the via chipset isn't good for overclocking but since it's free performance I thought I'd give it a go. After reading around the net about how HTT works in comparison to Skt A, I set about doing what I could.

To my surprise, I raised the FSB up to 240 (max the board allows) and everything is working fine. Why surprised?

Well, the board seems to have locked the DDR RAM at 400Mhz??? The HTT is still set at 4x (800 on a 754) and the PCI/AGP frequencies must be locked as well.

I thought increasing the FSB would increase the RAM frequency so I'd have to mess with dividers? Also the board has a "AI" overclocking feature, but all it seems to do it raise the FSB by a percentage.

Can someone shed some light on how everything is actually running at 240 FSB on skt 754? Surely it can't be as easy as just raising the FSB?

 

[bennny]

it is as easy as raising the fsb. and use CPU-Z to see what your actual fsb and what your ram is running at. Try looking for a mod'd bios that will allow you to raise your htt higher then that.

 

[Deanodarlo]

Thanks for the reply.

It's a cheap 754, so HTT won't go higher than 4x (800). Since the FSB is high, it's probably near 1000 anyway.

I'm just surprised the ram didn't crap out at 240 FSB - the boot up says it's still running at DDR 400 - but I'm sure that it can't be locked at that speed as everywhere on the net says lower your ram divider. My Skt A board would give the true DDR speed on boot at high FSB but perhaps this ASUS one doesn't. I'll have to wait and see.

Yeah, I'll install CPU-Z, but first I'll have to install WinXP. I was kind of hoping to get a quick answer here while I get it up and running.

 

[betasub]

It's possible your "boot up" display is from BIOS, and by DDR 400 it simply means that your RAM is running at 1:1, i.e. at the default divider. Quite often BIOS will label a memory speed based on the default FSB, e.g. DDR 333 if you are using a 5:6 divider, regardless of whether your FSB is actually over/under-clocked.

Another vote for CPU-z: in most cases it will show the real divider & resultant memory speed.

 

[DrMrLordX]

Originally posted by: Deanodarlo
Thanks for the reply.

It's a cheap 754, so HTT won't go higher than 4x (800). Since the FSB is high, it's probably near 1000 anyway.

You're having nomenclature problems here. Athlon 64/Sempron platforms do not have an FSB. They have an HTT. For our purposes, they're the same thing, but do remember that when people say HTT, they aren't talking about the multiplier (1x-5x), they're talking about the A64 FSB-equivelent.

The multiplier you referenced is either the HT multiplier or LDT.

I'm just surprised the ram didn't crap out at 240 FSB - the boot up says it's still running at DDR 400 - but I'm sure that it can't be locked at that speed as everywhere on the net says lower your ram divider. My Skt A board would give the true DDR speed on boot at high FSB but perhaps this ASUS one doesn't. I'll have to wait and see.

Yeah, I'll install CPU-Z, but first I'll have to install WinXP. I was kind of hoping to get a quick answer here while I get it up and running.

We can't tell you anything that your motherboard can't/won't, but don't be surprised if your RAM turns out to have more headroom than expected. It can happen, especially if your board overvolts your RAM by default. Try CPU-z, it should do you right.

btw, I wouldn't recommend installing windows while overclocked.

 

[Deanodarlo]

Thanks for the heads up. Yes, I'm new to the A64 scene so I'm learning as I go along.

The RAM was indeed running at 240 according to CPU-Z, but I've been reading that the PCI/AGP lock might not work on via chipsets. Indeed, if I set it to enable on the asus board it won't boot, without any overlocking! Auto works fine, but who knows what it's doing?

I'll probably just not bother overclocking on this board - don't want the AGP/PCI frequencies running at insane speeds.

 

[DrMrLordX]

The only thing wrong with AGP and PCI clocks running out of spec is if the devices themselves begin to malfunction. Continue with the 240 HTT overclock and see if the system exhibits any strange behaviors. Put it through the usual Prime95, Super Pi, 3dMark 2001 stress testing etc. Seems to me like you've got a pretty good OC on your hands considering the board.

 

[bennny]

download the newest bios and flash your mb. See if that helps with getting your pci lock in place. Then try running a ram divider and pushing the HTT farther. Lower the HT multiplier to 3x. Do this only after you have stress tested, and are sure the system is stable.