I'd use active cooling with that dual core chip. They don't run crazy hot but under a good load that passive heat sink won't be able to keep up with the cooling demands. Can you post a pick of the motherboard so we can see the mounting hardware.

Sure 😀 Here's some good pictures of the board that's in the 740:

I also found a picture of the heatsink itself:

If it's like another Dell I've got then that plastic cowl over the heatsink should have a fan sucking air through it.

snufkin wrote on 2021-05-07, 13:56:

If it's like another Dell I've got then that plastic cowl over the heatsink should have a fan sucking air through it.

Yes it does! It has the heatsink on the right under a plastic over and right next to it on the left there's a big fan

Sounds like the same arrangement then, so it is actively cooled, but by sucking rather than blowing air. The one I've got has a 2.8GHz P4 which, looking at random places on the internet, is apparently ~70W. The X2 5200+ is a bit more at 90W. So my guess would be you should be ok, but the fan might run fast a lot. I've never looked in to it, but I understand Dell motherboards can be a bit weird, so fitting a different heatsink might be tricky.

Ok if it has a duct to the back fan you should be good. What I would do is just put a higher cfm fan in and you should be good.

chrismeyer6 wrote on 2021-05-07, 14:15:

Ok if it has a duct to the back fan you should be good. What I would do is just put a higher cfm fan in and you should be good.

Hah, the one I pictured is a Dimension 5000, which has the duct pointing *forward* and out the front of the case. If you're wondering if that's noisy when it has to really spin up, then yes it is. Only rear fan is the PSU, also sucking air out of the case. No intake fans.

[oh, and the fan speed profile can't be changed, and there's no software access to the temperature sensor that I've been able to find]

snufkin wrote on 2021-05-07, 14:20:

Hah, the one I pictured is a Dimension 5000, which has the duct pointing *forward* and out the front of the case. If you're wondering if that's noisy when it has to really spin up, then yes it is. Only rear fan is the PSU, also sucking air out of the case. No intake fans.

[oh, and the fan speed profile can't be changed, and there's no software access to the temperature sensor that I've been able to find]

Ah yeah this one also points the air outward the case front. And i think i used hwinfo to read the temps.

snufkin wrote on 2021-05-07, 14:11:

Sounds like the same arrangement then, so it is actively cooled, but by sucking rather than blowing air. The one I've got has a 2.8GHz P4 which, looking at random places on the internet, is apparently ~70W. The X2 5200+ is a bit more at 90W. So my guess would be you should be ok, but the fan might run fast a lot. I've never looked in to it, but I understand Dell motherboards can be a bit weird, so fitting a different heatsink might be tricky.

Hmm CPU-World says it's 65W which is why i picked that one. Dell's Optiplex 740 leaflet which i was able to find also says the X2 5200+ is the max. CPU you can configure. I know it probably supports even better ones but this one seems the most safe to use 😀

Veo wrote on 2021-05-07, 15:08:

snufkin wrote on 2021-05-07, 14:11:

Sounds like the same arrangement then, so it is actively cooled, but by sucking rather than blowing air. The one I've got has a 2.8GHz P4 which, looking at random places on the internet, is apparently ~70W. The X2 5200+ is a bit more at 90W. So my guess would be you should be ok, but the fan might run fast a lot. I've never looked in to it, but I understand Dell motherboards can be a bit weird, so fitting a different heatsink might be tricky.

Hmm CPU-World says it's 65W which is why i picked that one. Dell's Optiplex 740 leaflet which i was able to find also says the X2 5200+ is the max. CPU you can configure. I know it probably supports even better ones but this one seems the most safe to use 😀

So it is. Or might be. Looks like there are a few listings for very nearly the same part and I only looked at the 89W part:
https://www.cpu-world.com/CPUs/K8/AMD-A ... ZBOX).html
https://www.cpu-world.com/CPUs/K8/AMD-A ... ZBOX).html

snufkin wrote on 2021-05-07, 15:21:

So it is. Or might be. Looks like there are a few listings for very nearly the same part and I only looked at the 89W part

Just checked, it's defo this one https://www.cpu-world.com/CPUs/K8/AMD-A ... OBOX).html 😀

I wonder, do other heatsinks/fans even fit on this board? I'm not that familiar with older boards and sockets.

Veo wrote on 2021-05-07, 15:27:

I wonder, do other heatsinks/fans even fit on this board? I'm not that familiar with older boards and sockets.

That I don't know. I think on other motherboards there's some sort of plastic bracket around the CPU socket, and the heatsink clamps on to that bracket. It that's the case here, then it looks like the holes in the motherboard for the bracket are there (don't know if they're in the right place), but some of the CPU power supply parts will get in the way.

You will need a Dell heatsink. The higher end ones like that are an actual decent heatpipe design and are mostly interchangeable between the different models that use that design.

One like this:

Part numbers are:
J9761
D9729

Here is the cheapest one I see on eBay for $12.99 shipped:
https://www.ebay.com/itm/184796190380

cyclone3d wrote on 2021-05-07, 16:29:

You will need a Dell heatsink. The higher end ones like that are an actual decent heatpipe design and are mostly interchangeable between the different models that use that design.

Ooh okay thanks! That does look like it will cool it better yeah 😀 I'm in Germany so i have to check ebay germany for those. Hopefully i'll find one

Not this amd Dell computers. There are two types of heatsinks, one for intel one for AMD due to processor package height and socket are different.

Only one heatsink for Optiplex 740 MT. AMD boards has socket normally posititioned, while Intel boards has processor rotated 45 degrees and different height.

Cheers,

pentiumspeed wrote on 2021-05-07, 16:37:

Not this amd Dell computers. There are two types of heatsinks, one for intel one for AMD due to processor package height and socket are different.

Only one heatsink for Optiplex 740 MT. AMD boards has socket normally posititioned, while Intel boards has processor rotated 45 degrees and different height.

Cheers,

Looking at pictures of both, the height looks to be about the same.

If the shroud is different, then maybe switching the heatpipe cooler to the heatsink shroud would work.... or modifying the shroud. OR even spacering the heatpipe cooler up a tiny bit on the stock shroud would work.

It has been years since I laid hands on one of the AMD Dell system like that so I am not entirely sure. It should definitely be possible to make the better cooler work with the AMD system though since the mounting brackets for the shroud should be exactly the same.

The 45 degree angle is not going to make enough of a difference to matter. The CPU die is in the middle and way smaller than the heatspreader.

Edit:
Looking at the mounting holes for your motherboard and for an Optiplex 780 motherboard, it looks like you would need to reposition the cooler in the shroud.. figure out how much you need to reposition the cooler to be centered over the CPU and then drill new holes to mount the cooler in the shroud and possibly remove a bit of other plastic which would prevent the repositioning.

The LGA775 socket is centered front to back while the AMD socket is not.

snufkin wrote on 2021-05-07, 14:11:

Sounds like the same arrangement then, so it is actively cooled, but by sucking rather than blowing air. The one I've got has a 2.8GHz P4 which, looking at random places on the internet, is apparently ~70W. The X2 5200+ is a bit more at 90W. So my guess would be you should be ok, but the fan might run fast a lot. I've never looked in to it, but I understand Dell motherboards can be a bit weird, so fitting a different heatsink might be tricky.

Just wondering, isn't it usually better when the fan blows towards the heatsink rather than away from it? I mean, the heat from the heatsink has to get to the fan and then out the case. But really if it's quite a hassle to put a different cooler in it, i might just have to leave it like this which is totally fine 😀

Quick update: Did a little test with CoreTemp last night, installing updates on Vista (Which takes some good 70% CPU) and the temps were at about 50°C, idle at about 30°C. That sounds promising to me 😀

Veo wrote on 2021-05-11, 10:18:

Quick update: Did a little test with CoreTemp last night, installing updates on Vista (Which takes some good 70% CPU) and the temps were at about 50°C, idle at about 30°C. That sounds promising to me 😀

Sounds good. I think, with the right ducting, that there's probably not much difference between blowing or sucking through the fins on the heatsink. The air has to come from somewhere, and if the ducting forces it to come from the far side of the cooler then the same heat will be shifted.

I don't know if it's still considered useful, but I still use Prime95 as a torture test. The blended mode seems to do a good job of alternating between stressing the CPU and the RAM (which would already have passed a 24 hour memtest86).