Sempron question

[cryptc]

I'm probably asking a really stupid question, but I just can't figure out the answer so here goes...

When studying the erols excellent list of cpu electrical specifications ( http://users.erols.com/chare/elec.htm ) I see two different Sempron 3500+ but with different power usage:

Sempron 3500+
(2.0GHz - 128KB) 1.25V 35W

Sempron 3500+
(2.0GHz - 128KB) 1.4V 62W

How can I know which of these two models are for sale at an online store when it only uses the Sempron 3500+ to signify what cpu it is? and why is there two identical cpu's whose only difference is that one draws twice as much power?

[disphenoidal]

If I recall correctly, for socket AM2 AMD released regular and EE (energy efficient) versions of many of their processors. According to another thread here, the EE ones are very difficult to find, possibly because HP purchased many of them for small form factor machines.

[cryptc]

are you sure? for it seems only the opterons have EE versions, and that's still part of their names...

[nici]

There is at least an EE version of the 3800 X2. Interesting how EE for AMD and EE for Intel stands for basically completely opposite things...

[cryptc]

hmm can't even find the EE processor you mentioned in the link above... maybe that site has some errors?

[jaganath]

How can I know which of these two models are for sale at an online store when it only uses the Sempron 3500+ to signify what cpu it is?

You can't, you need to know the part number to differentiate it (although it is much more likely to be the 62W, not the 35W version).

and why is there two identical cpu's whose only difference is that one draws twice as much power?

First of all, TDP does not equal power draw at all times, see below:

TDP and TCaseMax explained

Athlon 64 for Quiet Power pg 3

Secondly, the 35W CPU is the "Energy Efficient Small Form Factor" version of a normal Sempron, for very small mATX or SFF cases (as the name suggests), which are mostly only available to big OEM builders like HP (see the 7600Ps or whatever it is on the front page).

My guess is that you could get the power draw of a normal Sempron pretty close to an EESFF by undervolting.

Part number of the normal CPU is SDA3500IAA2CN, for EESFF it's SDD3500IAA2CN.

[smilingcrow]

AMD list the details on their site - Link.

[cryptc]

AMD list the details on their site - Link.

Thanks, that answered my question, although it was the answer I wasn't hoping for. When I look up the 3500+ Sempron here it lists two models, one 62W and one 35W... So I guess I can't know which one is for sale at a webshop when it only says Sempron 3500+, although from what people are writing here I guess I can assume it's the 62 W version...

[smilingcrow]

Thanks, that answered my question, although it was the answer I wasn't hoping for. When I look up the 3500+ Sempron here it lists two models, one 62W and one 35W... So I guess I can't know which one is for sale at a webshop when it only says Sempron 3500+, although from what people are writing here I guess I can assume it's the 62 W version...

The AMD site that I linked to shows the product codes for the various CPUs including boxed and tray versions. Most etailers should list the exact product codes that they sell, so you can determine what you are getting. Try typing in the product code for a 35W Sempron into Froogle for example and see what you get. In the UK the 35W semprons go for silly money; the 1.6 is £50 and the 1.8 which I think is the cheapest one that supports CnQ is nearer £75. Not that anyone seems to stock them!

[cryptc]

Well I'm in Norway, so don't have tonnes of options, but good news is I found some shops that carry the 35W versions (and labeled them as such)

[Poodle]

Dustinhome.se here in Sweden has/had them. After my order the Sempron 3000+ 35W went out of stock though. Dustin seem to have some Sempron 3200+ 35W left. They are cheaper at some other e-tailers but none of them has any in stock.

[kentc]

My guess is that you could get the power draw of a normal Sempron pretty close to an EESFF by undervolting.

second that. you'd probably have no problem running the 1.4v version at 1.25v or even less if you take it down a notch. so if there's a price difference you'd probably be just as happy (and cool) with the 1.4v version.

whichever you choose - undervolt to 1.1v, might work at full tilt or atleast at 1.6-1.8ghz.

kent.

[smilingcrow]

Can anyone confirm that only Sempron AM2s of 1.8GHz or higher support Cool ‘n’ Quiet? This means virtually all of them of course.

[nutball]

I can confirm that the 2800+ and 3000+ AM2 Semprons do not support C'n'Q (nor undervolting), and that the 3200+ does, if that helps. Can't speak for the others from personal experience I'm afraid.



(Psstt, anyone wanna buy some Sempron 2800+'s and 3000+'s still in their unopened boxes!).

While I'm at it I could have a mini-rant about how the retail packaging for both 2800+ and 3000+ say explicitly that they feature AMD's Cool 'n' Quiet technology. I do believe that that contravenes trade laws. Bad AMD, no cookie. *slaps wrist*.

[smilingcrow]

I can confirm that the 2800+ and 3000+ AM2 Semprons do not support C'n'Q (nor undervolting), and that the 3200+ does, if that helps. Can't speak for the others from personal experience I'm afraid.

Thanks, that’s the impression I was getting. They are at least consistent with the S754 Semprons in that only those with a multiplier of 9 or higher support CnQ. The confusing thing is that the S754 3000 (1.8GHz) does support CnQ whilst the AM2 3000 (1.6GHz) doesn’t.
I’m going to be buying a Sempron AM2 2800+ this week, so I’m interested. I can get one for £27.72 from Scan.co.uk with no extra for postage as its part of an order I’m already placing. Send me a PM on how much you want for it.

[jaganath]

I can confirm that the 2800+ and 3000+ AM2 Semprons do not support C'n'Q (nor undervolting)

That sucks. How can a CPU not support undervolting??? I know the S754's had Vcore locks, but at least you could undervolt a bit. The only point of the low-end Semprons is that you can downvolt them to <1V at stock speed and use them for surfing/watching DVD's etc. Who would buy a chip that has been crippled in this way?

[nutball]

I can confirm that the 2800+ and 3000+ AM2 Semprons do not support C'n'Q (nor undervolting)

That sucks. How can a CPU not support undervolting??? I know the S754's had Vcore locks, but at least you could undervolt a bit. The only point of the low-end Semprons is that you can downvolt them to <1V at stock speed and use them for surfing/watching DVD's etc. Who would buy a chip that has been crippled in this way?

Actually I should qualify that statement! The 2800+/3000+ can't be undervolted on the motherboard I'm using (ASRock ALiveNF4G-DVI). The board will happily undervolt to 0.8V in the BIOS for CPUs which support CnQ. The option isn't presented for the 2800/3000. It may be that other motherboards will allow undervolting for the non-CnQ CPUs. Yet another thing to try to keep track of when choosing a motherboard!

[jaganath]

The 2800+/3000+ can't be undervolted on the motherboard I'm using (ASRock ALiveNF4G-DVI).

Yeah, another poster had the same problem with an Asrock AM2NF3-VSTA; either it's purely an Asrock problem, or the non-CnQ AM2 Semprons don't undervolt (!?!).

PS. What do you think of the AliveNF4G-DVI? I run one w/ an A64 3800, will do a little experimenting to see what is the lowest voltage at stock speed.

[nutball]

PS. What do you think of the AliveNF4G-DVI? I run one w/ an A64 3800, will do a little experimenting to see what is the lowest voltage at stock speed.

It's not bad -- especially for the price. I think the only thing it's missing is GbE.

I've only had my 3200+ for half a day so I haven't had much time to fiddle with the voltages. I've got it running stable at [email protected]. At stock speed it's certainly happy at 1.15V, I haven't tried pushing below that at stock.

The major pain in the bum has been finding a decent heatsink for AM2 that'll fit in a Silverstone LC-11 (so <~70mm in height).

[Mariner]

The major pain in the bum has been finding a decent heatsink for AM2 that'll fit in a Silverstone LC-11 (so <~70mm in height).

The Asus X-Mars seems reasonable enough. The linked Madshrimps review indicates that the combined height of the heatsink and fan is just 62mm. Not sure if this is indeed the case or not though because the Asus website indicates the heatsink itself it a little bigger than this. Decent enough performance though obviously not earth-shattering.

The one problem is the 70mm fan because if it's too noisy you may struggle to find a quieter replacement. I'm looking at this one as a possibility for passive cooling however so this isn't really relevant!

I'm looking at the same ASRock board to and hopefully will get the opportunity to build system during the next couple of weeks. If I can fit it in around my hectic social calendar of course!

[corevalue]

I am undervolting a Sempron 3400 SDD model right now, at 1.0V, at stock multiplier (9x) and FSB, seems perfectly stable. It locks up at 0.975V. The core temp is 25.8C in a room at about 20C, and the mobo thermal sensor reports 28C...so the core is cooler than the chip.

To clear up the confusion: the difference between the 35W and 64W models is indicated in the third letter of the model number, assume all the ones you see for sale are 64W parts....I couldn't find a single SDO one to buy. Price for the low power model is premium too, up to 100% more.

[Palindroman]

I've only had my 3200+ for half a day so I haven't had much time to fiddle with the voltages. I've got it running stable at [email protected]. At stock speed it's certainly happy at 1.15V, I haven't tried pushing below that at stock.

Have you fiddled some more with the voltages?

I'm asking because I'm planning to build systems around the Sempron 3200+ (with an Asrock AliveNF4G-DVI mobo). The EE SFF Semprons are hard to get here in the Netherlands and so I've been thinking about undervolting a regular Sempron. I have no experience with undervolting, so it's nice to know beforehand what results have been obtained by someone else. What I still don't get: do you undervolt by changing the settings in BIOS or do you use a program like RMClock or CrystalCPUID?

[nutball]

Have you fiddled some more with the voltages?

It'll POST and boot to Linux at 1.075V at stock speed (1.8GHz), but not below that.

What I still don't get: do you undervolt by changing the settings in BIOS or do you use a program like RMClock or CrystalCPUID?

It depends on the motherboard -- some allow undervolting in the BIOS, with others you have to use a third-party application (which makes life tough if you're not running Windows). Broadly speaking I think BIOS undervolting is preferred around here; in some cases the CPU seems to refuse to be undervolted below 1.1V using the applications, but will happily take a lower voltage if applied through the BIOS.

The AliveNF4G-DVI and its larger brother the AliveNF6G-DVI both allow undervolting to 0.8V in the BIOS (it's under Advanced -> CPU configuration).

If you search around this forum there are several useful threads on how you should going about finding out that is the lowest voltage you can reliably operate at. (In summary -- work your way down from stock voltage until the machine refuses to POST. Then work your way up from the lowest POSTable setting until some stress test, eg. Prime95, will run for hours and hours without reporting an error). Every individual CPU will be different of course, so if you're going to build multiple machines you may have to do this individually for each of them if you want to extract the utmost from them.

Good luck!

[Palindroman]

Thanks for the quick answer, nutball!

It'll POST and boot to Linux at 1.075V at stock speed (1.8GHz), but not below that.

But if you lower the stock speed, you can lower the voltage, right? And if I understood correctly, once the computer needs more power it gears into higher speed and voltage. That's what I'm looking for with undervolting: the lowest power consumption possible at idle.

It depends on the motherboard -- some allow undervolting in the BIOS, with others you have to use a third-party application (which makes life tough if you're not running Windows). Broadly speaking I think BIOS undervolting is preferred around here; in some cases the CPU seems to refuse to be undervolted below 1.1V using the applications, but will happily take a lower voltage if applied through the BIOS.

The AliveNF4G-DVI and its larger brother the AliveNF6G-DVI both allow undervolting to 0.8V in the BIOS (it's under Advanced -> CPU configuration).

I aim to build low power systems and sell them to people, so it would be best if I can achieve minimum power consumption at idle through the BIOS, rather than through an application, of course. I can figure out how CrystalCPUID works and how you get it to start up every time the computer turns on, but you just can't explain things like that to clients and tell them not to touch anything.

If you search around this forum there are several useful threads on how you should going about finding out that is the lowest voltage you can reliably operate at. (In summary -- work your way down from stock voltage until the machine refuses to POST. Then work your way up from the lowest POSTable setting until some stress test, eg. Prime95, will run for hours and hours without reporting an error). Every individual CPU will be different of course, so if you're going to build multiple machines you may have to do this individually for each of them if you want to extract the utmost from them.

That's exactly what I mean to do with each system. At least until the EE SFF Semprons become more available. I found a lot of info here on undervolting etc, but except for this thread I haven't found much info on undervolting desktop Semprons (like a poll or something).

I'm going to build a test system in two weeks from now and will post my experiences here. In the meantime, one last question: Did you manage to measure the lowest power consumption of your undervolted Sempron system?

Thanks again.

[jaganath]

But if you lower the stock speed, you can lower the voltage, right?

Yes.

if I understood correctly, once the computer needs more power it gears into higher speed and voltage.

That's CoolnQuiet. You can fiddle with the P-states (voltage+clock speed settings) using CrystalCPUID/RMClock, but like you said, you don't want your clients to have to fiddle with that.

I haven't found much info on undervolting desktop Semprons

That's partly because the previous generation of Semprons (socket 754) had a Vcore lock which prevented undervolting below 1.1V, and partly because they run pretty cool out of the box. However, QuietOC did a lot of testing in that vein, ISTR he had a S754 Sempron 2500+(1.4Ghz) that ran at stock speed @ 0.88V.

[nutball]

But if you lower the stock speed, you can lower the voltage, right? And if I understood correctly, once the computer needs more power it gears into higher speed and voltage. That's what I'm looking for with undervolting: the lowest power consumption possible at idle.

As Jaganath said, that's Cool'n'Quiet. It's not at all clear to me how C'n'Q fits together with BIOS undervolting. The BIOS only allows you to set one voltage, whereas C'n'Q works by transitioning between various clock/voltage combinations depending on load. I don't think there are BIOSes which allow you to configure all the P-states for C'n'Q.

The default C'n'Q idle state is [email protected], so a fair bit above what my CPU is capable of running at, so it's not clear that C'n'Q would actually do the right thing in my system if it was enabled.

In the meantime, one last question: Did you manage to measure the lowest power consumption of your undervolted Sempron system?

It idles at about 49W (at [email protected]), or 55W ([email protected]). That's the consumption for the whole system from the wall. There's no hard-drive in it, just a small solid-state disk to boot Linux.

[Palindroman]

As Jaganath said, that's Cool'n'Quiet. It's not at all clear to me how C'n'Q fits together with BIOS undervolting. The BIOS only allows you to set one voltage, whereas C'n'Q works by transitioning between various clock/voltage combinations depending on load. I don't think there are BIOSes which allow you to configure all the P-states for C'n'Q.

Right, I get that. But what happens in your case, where you've got the system running at 1GHz and 0.925V, when the system needs more power? Do the voltage and clockspeed go up by themselves? I'm sorry I'm asking another silly question (I know how tiring that can be).

It idles at about 49W (at [email protected]), or 55W ([email protected]). That's the consumption for the whole system from the wall. There's no hard-drive in it, just a small solid-state disk to boot Linux.

Hmm, that's more than I hoped and expected, especially as you're running Linux without a hard drive.

[nutball]

Right, I get that. But what happens in your case, where you've got the system running at 1GHz and 0.925V, when the system needs more power? Do the voltage and clockspeed go up by themselves?

Nothing happens, as far as I'm aware. Basically I'm making a sacrifice. With the small difference in overall power consumption between 1GHz and 1.8GHz at their lowest voltages, it's not clear it's a sacrifice worth making of course.

It idles at about 49W (at [email protected]), or 55W ([email protected]). That's the consumption for the whole system from the wall. There's no hard-drive in it, just a small solid-state disk to boot Linux.

Hmm, that's more than I hoped and expected, especially as you're running Linux without a hard drive.

It sounds a lot, it's a bit higher than I was hoping too (was hoping for 40W), but I think it gets tough to push much below that using standard PC components, ie. without going the VIA-based mini-ITX route, or being *very* choosy about motherboards, etc. There are some other folks around here who have pushed down that far ... maybe they'll jump in an add some more info.

I think what it's saying is that one can obsess over a single component too much, and get blinded to the rest of the system. The CPU isn't the only factor in the equation, especially when one gets down to the sorts of lower power levels that Semprons pull. If you want the absolute lowest power you have to take a holisitic view of the whole system.

The system is living in a Silverstone LC-11, which has a 240W SFX power supply. I don't have any figures, but I doubt this is stunningly efficient PSU (it pulls 17W when switched off!). So of that 50W from the wall, maybe only 35W is going to power the motherboard & processor. NVIDIA chipsets don't have a global reputation for being low power, and I'm using the integrated graphics, so ... say 10W to the motherboard. A few watts to the memory and fans. So maybe the processor is in the 20-25W regime.

Put this in context -- this box is being built as an HTPC to replace my cable TV set-top box, which runs a Java operating system on a crappy 200MHz MIPS-based processor vvvverrrryyyyy sssslllooowwwlllyyy, and pulls 100W+ from the wall even in standby.

[jaganath]

So maybe the processor is in the 20-25W regime

At [email protected] I'd say even less, around 10-15W. Remember PSU's get much less efficient at very low power draws.

[Poodle]

Does anyone know if the Via 8K890 is lower power than the Nf 6100 and 6150 or not. Any tdp data?

6100 seems 10W cooler than 6150. But where does the Via fit in?


Looks like the chipset is the heat problem for the Amd uATX platform.