DDR stands for Dual Data Rate, so your DDR memory runs at a true speed of 200MHZ (for what we call 400MHz modules), but sends twice the amount of data compared to previous SDRAM
Perhaps one of the BIOS reports the true speed, and the other the "supposed speed" of the module?

Quick test: Swap memory modules and see if the "problem" is still there.

DDR stands for Dual Data Rate, so your DDR memory runs at a true speed of 200MHZ (for what we call 400MHz modules), but sends twice the amount of data compared to previous SDRAM

It's pretty clear from his post that he already knows that. You seem to have missed the fact that he's talking about DDR2-800, which indeed should be running at 400mhz, not 200.

However, I can't help but think that there's some sort of bug in the reporting on that Asrock board. It is a rather odd board, so it wouldn't surprise me if there were some hacks involved that confuse programs like CPU-z. And it doesn't sound to me like there's any actual performance issues, it's just misreporting the speed. You said yourself that the XP box is faster in some benchmarks, but it's also completely reasonable that it would be slower in some ways. It is, after all, quite different hardware and quite different OSes, and as such they're not going to perform the same in all things.

The same applies. I say 1st swap the modules to find out if the problem is in the motherboard. Then post a pic of the bios options so we can have a look.

Thanks for the replies. The memory is all identical:

Kingston HyperX DDR2 PC2-8500C5 1066MHz Dual Channel (KHX8500D2K2/4G)

I'll try to get some pictures.

I took a look at the manual for the Asrock board, and it appears the memory setting in the BIOS is located under Advanced->CPU Configuration->Memory clock. It's listed by clock speed rather than ratios, but the function is the same-- the listed memory speeds are relative to the stock HT base clock speed (often erroneously called FSB speed), so the 200mhz setting is 1:1, the 266mhz is 4:3, 333mhz is 6:5, and 400mhz is 2:1. I hate the way they do that, because it makes things confusing once you add an overclock to the mix as well... for example, an HT clock of 250 with a "266mhz" memory setting will result in an actual memory speed of 333mhz.

Nevertheless... check that setting. If the memory is set to 200mhz, and you're running a stock HT clock, then the memory is indeed only running at DDR2-400.

Yep, that's set correctly.

But looking at that page prompted me to load defaults, after which cpu-z reported memory at 400...

A few experiments seems to show that if I enable Flexibility Option [I will check again but I think that's the setting] then cpu-z reports 200mhz despite the memory clock setting. If I disable Flexibility Option , cpu-z reports 400mhz memory and the correct 5-5-5-18 timings.

edit - the program I mentioned above now runs in 23.5 seconds, which though slower than the 7 box seems within a reasonable range.

Boards like this can be very frustrating to use let alone tweak and I would try to find another 790x board if possible. Save this board though for the collection. As for tweaking it all I can say is good luck but you might be able to force some of the settings to get things working right.

this sounds like a stupid question, but the asrock board is running the latest official BIOS right?
forget about the brand of memory stick... what are the exact chips of the RAM?

did you post on hardocp asking if others experience this problem? I'm hoping it comes down to a buggy BIOS or a chipset issue

A few experiments seems to show that if I enable Flexibility Option [I will check again but I think that's the setting] then cpu-z reports 200mhz despite the memory clock setting. If I disable Flexibility Option , cpu-z reports 400mhz memory and the correct 5-5-5-18 timings.

Oh. Yeah. The 'flexibility option' is one of those weird things about Asrock boards that should always be disabled. It's an option they always include, and nobody is entirely sure exactly what all it does (it seems to do different things on every model of board), but the single common property about it is that it always screws something up.

Old Thrashbarg wrote:

It's an option they always include, and nobody is entirely sure exactly what all it does (it seems to do different things on every model of board), but the single common property about it is that it always screws something up.

🤣

I got very excited by these boards when PCI-E came along, for obvious reasons. I'd better check this setting on the others too.