So, I found a Q8400 quad-core 775 CPU. What to do with it?

Aug 25, 2001
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#1
I looked on ebay, there's a couple of sellers of ASRock 775 boards, the only ones that take DDR3 memory and are still available new. Cheapest is Newegg at ~$69 shipped.

Core2 is kind of played-out as a platform these days, although if the mobo takes DDR3, it's still maybe viable to build with? Have to add a video card (mobo has VGA output) for HDMI support, and possibly a dual-port SATA6G PCI-E x1 card for an SSD.

The thing is, I just hooked up my mATX Asus AM1 board with a Sempron 3850 1.3Ghz quad-core, which is overclocked 25%, to 125 FSB, 1.65Ghz, and even still running Win7 64-bit, the newest CPU-Z gives 103 for ST, and 403 for MT. By comparison, an E8500 3.16Ghz Core2Duo, scores 279 ST and 570 MT.

So even overclocked, and with twice as many cores, my AMD AM1 quad-core is like 3X slower in ST, and 1.5X slower in MT, than an older Intel Core2 dual-core chip. Crazy stuff.

So, I was thinking, this is a quad-core Core2 chip I've got, it still has some Cajones in it left, should I build a rig with it?

It only cost me $15 on ebay a year ago or so, so it's no big loss to toss it, or maybe resell it for the price of shipping.

Edit: I was thinking of my friend's Athlon II X4 640 3.0Ghz rig. If I throw 2x4GB of DDR3-1333 in the ASRock G41 mobo, and overclock the Q8400 from 2.66Ghz to 3.5Ghz (if I can, that is), then that would be a slight improvement, and then I could hook him up with a 260X 2GB GDDR5 video card, and a bigger SSD (I have a 240GB right now, or a couple of them), and re-install a fresh copy of Win7 64-bit for him, or install Win10 (rumor has it that the "free upgrade" is ending Real Soon Now), so I want to make sure that he doesn't miss the boat on that.
 
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Jan Olšan

Senior member
Jan 12, 2017
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#2
The improvement is going to be too slight to be worth investing money, mostly sidegrade (Penryn's only advantage is pretty much ssse3/sse4 for software that needs it, IPC is +-the same as K10). At that point, stash any money away for a more significant hardware refresh. That Athlon could be somewhat OCed too instead, couldn't it?

As for what to do with the CPU, keep it until you come across a LGA 775 Core 2 Duo/Pentium/Celeron machine where it can be used as a drop in upgrade without other expenses (well maybe except a better cooler if needed). That's efficient use of such find, not putting money into an essentially new "rig" that was hopelessly outdated yesterday.
 
Nov 13, 2017
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If I was you, I was going to use that Q8400 as a key-chain. :D
Anyway, If you have enough free time, some money to waste and you want to play with antiques then its OK whatever you do. But if you are asking from consumer perspective what to do then there is no point in wasting a cent for such an old calculator.
So, if you want a noticeable upgrade at minimum cost then sell all the antiques you have and add the money you are willing to waste to that sum. Then try to find newer used system, for example Haswell I5 with a cheap H110 mainboard. Even an i3 haswell would be a huge upgrade compared to all the CPUs mentioned in your post and with the savings from the electricity bills for a year or two you can upgrade it to i7. :D Good Luck with your new rig! ;)
 
Aug 25, 2001
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Well, in hindsight, I've basically decided to hold on to it. It wouldn't make much sense to build, and lose money on it. I might not even be able to give it away.

I guess, I end up with one part, and I automatically think, "Hey, let's build a rig!". Such a rush, LOL.

Anyways, I almost pulled the trigger on another i3-8100 and a Z370 ROG Strix-G or -F or something. It was $169.99 on Newegg's ebay store for the board. Almost. :)
 
Nov 13, 2017
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Well the "new" i3 are so "old" i5...and z370 mainboards are so expensive. If I was you for the same budget I was going to look at a B350 mainboard and a Ryzen 7 1600 for the same money. With or without OC it should wipe the floor with the i3 8100 in almost all the apps known to mankind.
 

DigDog

Diamond Member
Jun 3, 2011
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#6
hmm.. this just off the top of my head, but, doesn't the 8400 (which is essentially a Q6600 V2) take DDR2 ram?
 
Aug 25, 2001
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#7
hmm.. this just off the top of my head, but, doesn't the 8400 (which is essentially a Q6600 V2) take DDR2 ram?
No, it depend on the system chipset. The Core2-era CPUs didn't have a memory-controller on the CPU, they depended on the system chipset. Yes, Intel was still using their outdated "FSB" technology for Core2, unlike AMD's CPUs at the time that had an IMC.
 

DigDog

Diamond Member
Jun 3, 2011
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#8
so, not 775, but rather P35. AFAIK that was the first chipset that took DDR3. 775 took DDR2, because that's what i had in my Gigabyte DS3.
 
Aug 25, 2001
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so, not 775, but rather P35. AFAIK that was the first chipset that took DDR3. 775 took DDR2, because that's what i had in my Gigabyte DS3.
No, 775 wasn't a chipset, that was the socket type. There were multiple chipsets that supported socket 775 CPUs.

You're right that P35 was one of the first chipsets to support DDR3.
 

DigDog

Diamond Member
Jun 3, 2011
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#10
wait, now you got me confused. were Conroe boards ALSO called 775, chipset AND socket? because i've always known my board as a 775.

hmm, never mind. the chipset was in fact P965 (brilliantly marketed by gigabyte as 965P), not 775.
 
Nov 13, 2017
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Q6600 V2 is a Q6600 Rev G0 which OC much better than the Q6600 B3. The Q6600(Kentsfield) is 2.4GHz(9x266) with 2x4MB L2 FSB1066 65nm, while the Q8400(Yorkfield) 2.66GHz(8x333) 2x2MB L2 FSB1333 45nm is a derivate with only 1/3 of the available L2 enabled. The Q6600 is a much better option for OC since it has higher multiplier and a 20% more FSB and RAM divider headroom. With DDR2-800 and cheap P965 mainboard the G0 Q6600 were capable of stable 3.6GHz OC(9x400MHz). Q8400 with the same mainboard and RAM modules could barely OC more than 3.2GHZ(8x400MHz).
Anyway, if someone wants to build a Core2 Quad system I will recommend him to find the dirt cheap Xeon LGA661 Yorkfield CPUs which with a simple modifications can be used on LGA775 P35/P45/G43 mainboads. Several years ago I bought such 3.16GHz(9.5 x 333) 2x6MB L2. These CPUs can easily be OC-ed to 3.8GHz and are performing dramatically better than Q8400 due to the 3x larger L2 caches.

As for the FSB and IMC, these are two different things and are not related to each other. It was just Intel who had the memory controller on the chipset and was using "outdated" FSB to connect the chipset with the two dies on the MCM CPUs (Pentium 4/EE and Core2). Unlike Intel, AMD starting with their Athon64 CPUs moved the MC to the CPU and started using direct point-to-point connection called HT. Now with ZEN AMD are back to the "outdated" FSB with ZEN's InfinityFabric, but with a difference that now the chipset is included in the CPU or the so called SoC (System on a Chip).
 
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ao_ika_red

Golden Member
Aug 11, 2016
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If giving it away as a Christmas present to your younger relative is not your cup of tea, I think running it stock is not a bad idea. Just look for multi-threading capable software to mask its lowly ST performance.
For me, OC-ing a decade old tech won't justify extra energy needed to achieve marginal performance gain.
 
Aug 25, 2001
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Now with ZEN AMD are back to the "outdated" FSB with ZEN's InfinityFabric, but with a difference that now the chipset is included in the CPU or the so called SoC (System on a Chip).
I completely disagree. AMD never used Intel's FSB. The last CPU that they used a FSB on was the Athlon XP.
 
Apr 27, 2000
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The last time AMD used Intel's FSB was either Socket 7 or Super 7, depending on whether or not you consider the bus protocol to have changed enough by the K6-III era to represent an actual difference. I'm pretty sure Super 7 was the same bus though, just at higher clocks.

Once Athlon rolled out, AMD was using DEC's EV6 BUS, which was not Intel's.
 
Nov 13, 2017
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I completely disagree. AMD never used Intel's FSB. The last CPU that they used a FSB on was the Athlon XP.
AMD used the FSB starting from their first x86 CPU, the K5, until K8. From K8 to ZEN the AMD CPUs were using HTT as a direct point-to-point connection to the chipset and to other CPUs, while the Northbridge including the Memory Controller was moved to the CPU, where the IMC was directly connected by an independent 144bit bus (Dual Ch. DDR ECC). (Kudos to Jim Keler, the K8 and the ZEN designing teams leader).

ZEN, although equipped with HTT links in its Data Fabric, is using the very same FSB concept where the links are shared point to multi-point connections of multiple sources which are competing for I/O. That involves all the CCXs and the IMCs in the system regardless of the number of CCXs, dies and CPUs. What may confuses you maybe is the fact that the IMCs on ZEN are on the CPUs. That's true but the used concept is the FSB concept. The ZEN SoC has the Northbridge integrated to the CPU, where the DF is a router connecting all the I/O on the system. The Intel Pentium4/Core2 FSB system has a separate Northbridge chipset which does the same as ZEN's DF. The Northbridge has the IMC connected to it and has a connection to both dies on the Core2 or the two CCXs on Ryzen. Whenever a core is accessing a data from the RAM or from the others die cache it has to go through the FSB and the Northbridge where the IMCs are connected on the Core2 Quad system. The same applies with Ryzen where the core has to go through the HTT link and the DF where the IMCs are connected on the Ryzen CPUs. When accessing others die cache the FSB on Core2, just like the DF on Ryzen, are badly starving for bandwidth(needs 10 times more). When accessing RAM at same time it becomes even worse because now the same FSB/HTT has to be shared. The access latency in both cases, via the FSB and Northbridge on the Core2 and via the HTT and DF on the Ryzen, is critically higher compared to architectures with unified last level cache and directly connected IMCs. Although AMD did the the MCM-FSB concept on a higher tech-level with Zen, did not solve any of the bottleneck and performance issues of Intel Core2.

To make a better image of what is ZEN, look at it like a multi CPU system where each CCX is an independent CPU, while the Infnity Fabric is the Northbridge Chipset(s) sharing the "slow FSB" as system bus to connect all the CPUS to each other and to the MC and the rest of the I/O.
 
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LightningZ71

Senior member
Mar 10, 2017
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The q8400 and it's generational bretheren have a very specific remaining use case. There were many, many Dell Optiplex 780 towers and desktops (and the equivalent HP models) sold to businesses over the years. Most of them had the absolute slowest possible processor in them for cheapness and are available on the used market for very, very low prices. The q8400 is a drop in upgrade for many of them that takes them from a tiny cache uni or dual core clunker to a modestly capable desktop. With 4 GB of RAM and the cheapest possible SSD, it makes for a fine internet cruiser with Windows 10. If you can find some old 600 series Nvidia video cards like the 630 which can be had cheap used, it can competently handle e-sportd and modest general gaming as well. I should know as I do this a lot and make about $50 a pop for turning them for people. This will stop when MS starts preventing the windows 10 upgrades/installs for them as most came with Windows 7.
 

scannall

Golden Member
Jan 1, 2012
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The q8400 and it's generational bretheren have a very specific remaining use case. There were many, many Dell Optiplex 780 towers and desktops (and the equivalent HP models) sold to businesses over the years. Most of them had the absolute slowest possible processor in them for cheapness and are available on the used market for very, very low prices. The q8400 is a drop in upgrade for many of them that takes them from a tiny cache uni or dual core clunker to a modestly capable desktop. With 4 GB of RAM and the cheapest possible SSD, it makes for a fine internet cruiser with Windows 10. If you can find some old 600 series Nvidia video cards like the 630 which can be had cheap used, it can competently handle e-sportd and modest general gaming as well. I should know as I do this a lot and make about $50 a pop for turning them for people. This will stop when MS starts preventing the windows 10 upgrades/installs for them as most came with Windows 7.
Also, the iMacs from that era were the Core 2 Duo's. And the q8400 is a drop in, instant upgrade. One I did to an old iMac I had some time ago.
 
Aug 25, 2001
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#18
AMD used the FSB starting from their first x86 CPU, the K5, until K8. From K8 to ZEN the AMD CPUs were using HTT as a direct point-to-point connection to the chipset and to other CPUs, while the Northbridge including the Memory Controller was moved to the CPU, where the IMC was directly connected by an independent 144bit bus (Dual Ch. DDR ECC). (Kudos to Jim Keler, the K8 and the ZEN designing teams leader).

ZEN, although equipped with HTT links in its Data Fabric, is using the very same FSB concept
When someone writes "FSB", generally-speaking, they are referring to the QDR FSB protocol used by the Intel Pentium 4 and Core2 era CPUs. The 486 CPUs, granted, did use an Intel protocol, but it was not the same "FSB" that the P4 used, IIRC. While AMD shared a bus protocol for their reverse-engineered 486 CPUs that were drop-in replacements, I don't consider those to be "FSB".

And just because AMD chose to use a similar topology in Zen, does not mean that it in any way resembles the Intel FSB protocol, which was largely thought of as outdated and inefficient, two things that Zen ARE NOT.
 
Sep 7, 2001
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#19
Get a board from Ebay like these for as cheap as you can (from a reputable seller):

Mobo from Lenovo ThinkCenter M58/P (Intel Q45+ICH10DO) a.k.a. MTQ45MK or L-IQ45 "Panda"

IIRC, the Lenovo board may need thermal monitoring sense cable in order to get rid-off the POST warning when not connected, which can be had for an extra $5 or $6. I don't think the BIOS has option to disable the temp sensor cable check.
 
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Ferzerp

Diamond Member
Oct 12, 1999
6,426
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#20
When someone writes "FSB", generally-speaking, they are referring to the QDR FSB protocol used by the Intel Pentium 4 and Core2 era CPUs. The 486 CPUs, granted, did use an Intel protocol, but it was not the same "FSB" that the P4 used, IIRC. While AMD shared a bus protocol for their reverse-engineered 486 CPUs that were drop-in replacements, I don't consider those to be "FSB".
This is in no way correct. Front side bus as a term was in use for ages before what you are attributing it to. Just look at this article for example. https://www.anandtech.com/show/556. We could go back even further if we wanted. The original poster was correct. You aren't.

edit: let's go back 3 more years. https://www.anandtech.com/show/4
 

Smoblikat

Diamond Member
Nov 19, 2011
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No, it depend on the system chipset. The Core2-era CPUs didn't have a memory-controller on the CPU, they depended on the system chipset. Yes, Intel was still using their outdated "FSB" technology for Core2, unlike AMD's CPUs at the time that had an IMC.
AMD had a truly bulletproof IMC at that time too, I pushed 2.25v through some very unfortunate DDR3 on a PH2 X2 555. IIRC P45 was mostly DDR2, while X38/X48 had DDR3 with an S775.

I used to have a Maximus rampage.......or somthing like that, had an X38(X48?) chipset and supported DDR3, plus I could clock my QX9770 to the moon and back (4.0 as I recall, with 4X2gb corsair dominators), paired with Tri-fire 4870's It was almost as top of the line as you could get at the time.
 

Ferzerp

Diamond Member
Oct 12, 1999
6,426
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#22
I suspect the date on that last link to be wrong. It was probably from 1998 or so since the P2B was a 440BX which google tells me was released in early 1998 and not 1997.
 
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Aug 25, 2001
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#23
This is in no way correct. Front side bus as a term was in use for ages before what you are attributing it to. Just look at this article for example. https://www.anandtech.com/show/556. We could go back even further if we wanted. The original poster was correct. You aren't.
Shrug. I mean, when PC people refer to "molex", technically they are referring to any plastic connector made by the Molex company, of which there are several in use in the PC. But in the vernacular, they are referring to the 4-pin peripheral connector, used by IDE HDDs. Same deal with "FSB".
 

Ferzerp

Diamond Member
Oct 12, 1999
6,426
1
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#24
Shrug. I mean, when PC people refer to "molex", technically they are referring to any plastic connector made by the Molex company, of which there are several in use in the PC. But in the vernacular, they are referring to the 4-pin peripheral connector, used by IDE HDDs. Same deal with "FSB".
I am part of "people," and I do not agree with you. The links are evidence that that term has been used casually in computing circles in a manner that doesn't align with your narrow definition. The person you were correcting was perfectly fine with that usage.
 

ViRGE

Elite Member, Moderator Emeritus
Oct 9, 1999
31,518
2
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#25
When someone writes "FSB", generally-speaking, they are referring to the QDR FSB protocol used by the Intel Pentium 4 and Core2 era CPUs. The 486 CPUs, granted, did use an Intel protocol, but it was not the same "FSB" that the P4 used, IIRC. While AMD shared a bus protocol for their reverse-engineered 486 CPUs that were drop-in replacements, I don't consider those to be "FSB".

And just because AMD chose to use a similar topology in Zen, does not mean that it in any way resembles the Intel FSB protocol, which was largely thought of as outdated and inefficient, two things that Zen ARE NOT.
IMO, if we wanted to talk about the AGTL+ FSB then we'd call it the AGTL+ FSB. Similarly, if we wanted to talk about the EV6 FSB, then we'd use that.:p
 


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