Yet another Optiplex 745 CPU upgrade question

[Luigi_Master]

I apologize if this is sent to the wrong section, I just simply used the 'ask the community' tab on the top. Feel free to move it if it is wrong.

Hello, Tom's Hardware. I have recently come across an Optiplex 745, which according to my research uses the venerable LGA 775 socket type. I've also done some research regarding the Xeon CPU mods, and it turns out that Dell PCs are more limited than custom motherboards, but I believe you can still use Xeon CPUs with hacked BIOSes. However, I have not been able to find anything about the Optiplex 745, only about the Optiplex 755, such as this on Delidded.

http://www.delidded.com/lga-771-to-775-adapter/3/#dell

So my question here is simple; is the 745 similar enough to the 755 so that I can undertake this mod? If so, would I need server RAM, since it's a server CPU? If not, should I just upgrade from the Core 2 Duo E6700 and put in a Core 2 Quad Q6600? Or since it's a Dell motherboard which likely has limited overclocking, should I get a Q6700 instead? I have been told by a person who sells the Xeon 3363s that the 745 is incompatible with that processor, and advised me to get a 755 motherboard and swap it out. I think that would be too much effort and money for what appears to be a negligible boost in performance over the C2Q.

If you need any more information, feel free to ask. I'm planning on modding this PC and slapping a small GPU in it so that I can hand it off to my nephew. Here are some screenshots from Speccy, if these will help.

http://i.imgur.com/mQl1WxU.png
http://i.imgur.com/2gNWu0n.png

Thank you, and I hope to hear from you soon.

 

[NukaB]

I don't believe you would need server ram. Server RAM is generally ECC memory, built specifically for servers and is an expensive variant.

Your current mobo probably won't support overclocking; apparently you have a Q965 chipset, and 9/10 of the time OEM parts such as that won't allow for changing frequencies in the BIOS. A C2Q Q6600 will serve you well but you might want to look at the 8000 and 9000 series as the price difference between those and the 6000 series is negligible.

 

[Luigi_Master]

I don't believe you would need server ram. Server RAM is generally ECC memory, built specifically for servers and is an expensive variant.

Your current mobo probably won't support overclocking; apparently you have a Q965 chipset, and 9/10 of the time OEM parts such as that won't allow for changing frequencies in the BIOS. A C2Q Q6600 will serve you well but you might want to look at the 8000 and 9000 series as the price difference between those and the 6000 series is negligible.

Thank you for the answer, I appreciate it! So are you saying I could instead drop a Q9650 in this old Dell? I remember reading, though I may have read it wrong, that motherboards with 65nm CPUs (such as mine) can only accept other 65nm chips, such as the Q6xxx series. If I can instead drop a Q8 or Q9 series, then I can just go with either of those, and chose the best one regarding price.

Speaking of RAM, the FSB of the C2D and C2Q is 1066MHz. Would that mean that the optimal RAM speed this PC could use would be 1066MHz? Because 1066MHz RAM seems to be much more expensive than 800MHz, and I was wondering if I'd lose any performance going with the cheaper route.

Thanks again, hope to hear back!

 

[NukaB]

Just googled that; seems that is the case! Never come across that before. Have you looked at the QX series? The Q6600 isn't a poor CPU, but it's always worth looking at better options.

The difference between 1066Mhz and 800mhz will probably be negligible in most use. In games, you'd likely only be able to see a 1-2fps drop, if that. Day to day operation of the computer probably won't be any different, so you may as well stick with 800.

 

[Luigi_Master]

Just googled that; seems that is the case! Never come across that before. Have you looked at the QX series? The Q6600 isn't a poor CPU, but it's always worth looking at better options.

The difference between 1066Mhz and 800mhz will probably be negligible in most use. In games, you'd likely only be able to see a 1-2fps drop, if that. Day to day operation of the computer probably won't be any different, so you may as well stick with 800.

While the Kentsfield XE CPUs are indeed 65nm, I'm not sure if I can use them due to them having a significantly higher TDP relative to the Core 2 Duo or Quad, though the Quad is a 105 W CPU versus the C2D's 65. If I can use the QX6850, then that will be the strongest CPU I could slap into this PC, however it's a very pricey piece, 46 dollars versus the Q6700's 22.50 or Q6600's 15. Any second opinions, is the 6850's additional power, if significant, worth it over the others?

 

[william p]

I did an overclock on an Optiplex 745. You need to understand what you have first. It supports Pentium 4 and PentiumD CPUus and early 65nm Core2 Duo.
This is good because it means it can support 120W CPUs. The fastest is the Core2Extreme QX6800 2.93GHz Quad core. It can handle 8GB DDR2-800 memory also.
It won't support any 32nm or 1333 fsb chips. Other options would be Q6700, QX6700 at 2.66, or X6800 2.93 2 core.
See "Overclocking Dell BTX Computers". If that interests you Then the QX6800 SLACP is the one to get. Lower power draw G0 stepping let's it get up to 3.45GHz. Cooler D9729 bolts in. T9303 fits with mods. Not neede at 3.2Ghz level.
The VRM section is weaker than others from this era. 3 phase and 2 chips per. Heatsinks there will be needed.

 

[Luigi_Master]

I did an overclock on an Optiplex 745. You need to understand what you have first. It supports Pentium 4 and PentiumD CPUus and early 65nm Core2 Duo.
This is good because it means it can support 120W CPUs. The fastest is the Core2Extreme QX6800 2.93GHz Quad core. It can handle 8GB DDR2-800 memory also.
It won't support any 32nm or 1333 fsb chips. Other options would be Q6700, QX6700 at 2.66, or X6800 2.93 2 core.
See "Overclocking Dell BTX Computers". If that interests you Then the QX6800 SLACP is the one to get. Lower power draw G0 stepping let's it get up to 3.45GHz. Cooler D9729 bolts in. T9303 fits with mods. Not neede at 3.2Ghz level.
The VRM section is weaker than others from this era. 3 phase and 2 chips per. Heatsinks there will be needed.

Hey, thank you for the answer, William! I did some looking around for the QX6800, and it seems to be an exceptionally expensive chip. Should I really invest the 70 bucks for the QX6800 over the $25 Q6700? I also seen an X6800 for 35 bucks, but that's a dual core. It seems like a pretty steep price for what is essentially an old, obsolete part.

I know the X series offer overclocking, but aren't the Dell BIOSes locked to prevent that? Additionally, you said that the motherboard is a bit weak, making overclocking a bit more limited as well. Let's suppose I got the QX6800, a custom cooler, and wanted to overclock, what is the maximum stable speed the Dell's weak VRM will allow?

 

[william p]

It depends on how fast you want to go. I've had my E520/SLACP up to 4GHz (see the link in my sig). But you won't get near that with the 745 so you have a valid point. The 745 won't support 1333 fsb that's why the QX6850 isn't listed. if you don't want to O/C the q6700 is G0 stepping and will clock up nicely on a board that supports 1333 fsb. The QX6700 is B3 stepping and they tend to run OK at 3.2GHz. Dell and Gateway sold systems with that spec. The X6800 can go 3.72GHz if you don't need 4 cores. I ran it but did no load testing. The QX6800 is the fastest 65nm quad and the SLACP versions cost the most. With a weak VRM the B3 version won't be any better than the QX6700. The steps are 1 whole multiplier. So it's 3.2-3.45-3.72-4GHz. QX6700 @ 3.2 is cheap and easy. VRM is probably OK at that level. The GPU makes more difference any way and that can be the hard part.
The overclock is done in Windows. I used Throttlestop6.00. There are no 2.93 Ghz 65nm /1066fsb except the 6800 Extremes. Otherwise it's 2.66 GHz without an overclock. I suggest the QX6700 and try the O/C. The software is free.
3.45 was all I could get out of the SLACP QX6800. There are no aftermarket coolers for BTX. The number I gave is a Pentium D heatpipe cooler. $10-15 surplus.

 

[Luigi_Master]

It depends on how fast you want to go. I've had my E520/SLACP up to 4GHz (see the link in my sig). But you won't get near that with the 745 so you have a valid point. The 745 won't support 1333 fsb that's why the QX6850 isn't listed. if you don't want to O/C the q6700 is G0 stepping and will clock up nicely on a board that supports 1333 fsb. The QX6700 is B3 stepping and they tend to run OK at 3.2GHz. Dell and Gateway sold systems with that spec. The X6800 can go 3.72GHz if you don't need 4 cores. I ran it but did no load testing. The QX6800 is the fastest 65nm quad and the SLACP versions cost the most. With a weak VRM the B3 version won't be any better than the QX6700. The steps are 1 whole multiplier. So it's 3.2-3.45-3.72-4GHz. QX6700 @ 3.2 is cheap and easy. VRM is probably OK at that level. The GPU makes more difference any way and that can be the hard part.
The overclock is done in Windows. I used Throttlestop6.00. There are no 2.93 Ghz 65nm /1066fsb except the 6800 Extremes. Otherwise it's 2.66 GHz without an overclock. I suggest the QX6700 and try the O/C. The software is free.
3.45 was all I could get out of the SLACP QX6800. There are no aftermarket coolers for BTX. The number I gave is a Pentium D heatpipe cooler. $10-15 surplus.

Alright, so you basically said that, due to the Dell's motherboard, the overclock of the QX6800 won't be significant, and a QX6700 would be my next best bet. It seems a bit more expensive than the regular Q6700, but I assume it's because it allows for easier overclocking with that software like FrontFSB, right?

 

[william p]

I was busy for a couple days. But I'll give you my suggestion for a budget 745 build. Then my comments on overclocking.
Get latest BIOS from Dell (updates CPU, Memory capacity and speed, PCIe version)
Cooler D9729 (rated for PentiumD and P4 over 3.4Ghz) bolts in.
QX6700 for easy overclock.
At least 5GB DDR2 800 RAM. ( get 2X2GB 800, and use what you have now,probably 667, go to 8GB@800 later).
GTX750Ti 2GB DDR5 (Legacy BIOS not EUFI) Single fan 2 slot fits if you cut bracket in 1/2, might need to cut cover for air to go out rear vent.
HD720P flat screen TV (good fps and detail with GTX750).
Options- Bigger PSU either Dell T3400 375W 6 pin PCIE, T3400 525W 2x 6pin PCIe, or aftermarket with 22a on 5V. rail. ( Dell wires are right length for BTX). I have installed up to EVGA 850W in these. Newer DVD drives are shorter than old ones.
Then GTX950Ti for 1080P, or ITX video cards with trimming to clear heatsink cover. 4GB ITX cards are rare. (known issue with Sapphire R9-285/380 ITX) HD7xxx / R9-280 work OK. Nvidia no known issues.
Antec expansion slot blower to pull heat out from behind GPU area.
Throttlestop 6.00 controls voltage and multiplier on LGA775 systems including overclock on Core2 Extremes also displays Temp. can be adjusted on the run, no reboot. Very stable due to all chips running at normal speed except CPU. 3.2GHz is 20% OC and should equal Q9550/9650 performance. This was stock speed on some XPS systems.
SetFSB etc. limited results due to lack of voltage control, works best with VID pinmod. Q6700 would be better chip for this method. Results uncertain due to pushing PLL out of range. I can't say more because it didn't work for me. Memory and PCIe timing can be effected.
BSEL pinmod not suitable for this due to no higher FSB in this chipset. VID pin mod needed also.

 

[Luigi_Master]

I was busy for a couple days. But I'll give you my suggestion for a budget 745 build. Then my comments on overclocking.
Get latest BIOS from Dell (updates CPU, Memory capacity and speed, PCIe version)
Cooler D9729 (rated for PentiumD and P4 over 3.4Ghz) bolts in.
QX6700 for easy overclock.
At least 5GB DDR2 800 RAM. ( get 2X2GB 800, and use what you have now,probably 667, go to 8GB@800 later).
GTX750Ti 2GB DDR5 (Legacy BIOS not EUFI) Single fan 2 slot fits if you cut bracket in 1/2, might need to cut cover for air to go out rear vent.
HD720P flat screen TV (good fps and detail with GTX750).
Options- Bigger PSU either Dell T3400 375W 6 pin PCIE, T3400 525W 2x 6pin PCIe, or aftermarket with 22a on 5V. rail. ( Dell wires are right length for BTX). I have installed up to EVGA 850W in these. Newer DVD drives are shorter than old ones.
Then GTX950Ti for 1080P, or ITX video cards with trimming to clear heatsink cover. 4GB ITX cards are rare. (known issue with Sapphire R9-285/380 ITX) HD7xxx / R9-280 work OK. Nvidia no known issues.
Antec expansion slot blower to pull heat out from behind GPU area.
Throttlestop 6.00 controls voltage and multiplier on LGA775 systems including overclock on Core2 Extremes also displays Temp. can be adjusted on the run, no reboot. Very stable due to all chips running at normal speed except CPU. 3.2GHz is 20% OC and should equal Q9550/9650 performance. This was stock speed on some XPS systems.
SetFSB etc. limited results due to lack of voltage control, works best with VID pinmod. Q6700 would be better chip for this method. Results uncertain due to pushing PLL out of range. I can't say more because it didn't work for me. Memory and PCIe timing can be effected.
BSEL pinmod not suitable for this due to no higher FSB in this chipset. VID pin mod needed also.

Alright, thanks for the heads up. I got myself a Q6700, it should do the trick. Thanks.