Reply 180 of 208, by CwF
Yes, past a few cores there is little gain, cooling is challenging if you actually use all the available power, which is hard if not impossible - BUT, with the bios control mentioned, and the realization your never going to get full throttle anyway - there is a way out!
First, disable HT. If you have a need for the cores, build in more! you cannot use all the cores you can have -speaking XP32 here. Where I use handbrake this is still true, though not XP32. Disabling HT is good for smoothness, and provides some clocking headroom, and gains a 10-15% thermal headroom. Again, we are re purposing 2nd hand here, we can afford the obvious blasphemy of literally castrating a formerly high end cpu...
Next, you don't have to run all the cores. Same thought as the HT, but a little more rude to the pride of a high end xeon. Most bios's on a 5500 series X8 will allow 1,2,3,4,5,6 cores per socket. Again, adjustable thermal advantage. My floppy mentioned XP is what I ended up with after building on X8's with linux, multiple X8DTHxxx variants. I bought a X8DTi to recycle cpu's and memory after I noticed the chipset drivers on the CD and did a test nlited XP install on a 7 slot dual 5520 beast (X8DTH-i) that came up clean, though not really useful. The X8DTi-F install was clean too (qd3nodrv.inf), and correct sata from boot, and offers the floppy port and PCI. With dual 5687's as 2 core it will run with supermicro 4 pipe coolers and 900-1200rpm quiet 4pin replacement fans almost silently. Also in the bios you can force a LOWER multiplier for 100% duty NON-turbo. This really help the thermals yet will not restrict full turbo speed, that will game firstname.lastname@example.orgGhz all day without noise. It sports an AMD Sky 500 16lane 4GB ECC working at full capability on XP32, and also is passively cooled. The swap is part of the PAE ram drive, 20.99GB of the 24 installed, it has passed with 48GB, 24x4, triple channel, fastest is 6 dimms only for full 1333 speed iirc. I think PAE can handle 64GB.
Usually I run all 4(x2) cores, no HT, and 18 cmos ratio. That's 2.4 limit non turbo, and like I said that does not limit the turbo, it just limits the mid clock, so it holds 2.4, or pegs 3.9ish. not 3.6 as rated. I never hear it.
Turn on HT and compile a kernel with t-16 and you will hear the OH alarm in about 20-30 minutes when the sockets hit 96C. In the 'archival fun' configuration as explained the cpu's range in the 70-80's, as does the gpu. It's in a wide body tower from the 90's that once housed my P3TDe-6. I made the 80pin backplane, ripped it out, modded the front cage to clear the board, etc.
No to the special power supply, not an issue, it runs a miniATX 500w PS that does have a 24 pin but I needed to fake it on the extra cpu connections, One 4 pin in each 8 pin is good enough, again, it takes effort to actually load these things to their max and an XP32 can't come close. As configured I measured 288W at the wall with effort to do so, I recorded mid 90C cpus and 97C GPU - and QUIETLY! In real use that peak is rare. With Debian or some other proper 64 bit OS it could maybe melt...The lack of a rack of scsi drives makes a huge difference, no, I don't miss that 'genuine' mess.
My favorite to date for my general use is still X9's. I have a X9SRA for single tasking and a X9DAi (3 pci-e x16 gpu's)for server crunching. That X9D is in a 19" rack case I modded into my desk when it had a P6SGU or DGe something...also in the 90's, I still have an AT rear plate for it) Nothing has excited me since. Past favorites of the single cpu variety; C7Q67 (E3 Xeon modded) and X9SCV-Q run XP32 well. C2SBC-Q's were fantastic workhorses that could overclock some and should be very compatible for older OS's.
I used to know what I was doing...